Oh yeah, you're more or less right. I quit WoW in Legion and flirted with the idea of coming back when all the...well, you know...happened that more or less killed that drive completely.
But, when posting that, I did go and look up IcyVeins, which I'm guessing is still current. From what I can tell, the current Resto rotation has one of two aspects:
Balance affinity is basically current WHM with slightly more interaction. You have Wrath (Glare), Moonfire (Dia), and Starfall (Holy), and then a couple of abilities that don't PERFECTLY match WHM 1-to-1 but have near-adjacent parallels. Starsurge can be thought of to SORTA be like how WHM uses Lilies and then Misery, and Sunfire can be thought of KIND of like Asize (an AOE cleave) if it was a GCD, or alternatively Starsurge would be our Asize and Sunfire...has no equivalent since we don't have Aero 3 (a spell I WOULD like added back to FFXIV). Sunfire can be spammed, but that's a poor choice since you'd generally just apply it and then spam Starfire, using Starsurge on CD. There are some interactions - Starsurge boosting the next damage of Wrath if in Solar or crit of Starfall if in Lunar - but these are largely "use Starsurge on CD and keep casting Wrath or Starfall, respectively". So while there's an interaction ON PAPER, it's arguably little different to how we play WHM today, using Assize on CD and spamming Glare or Holy, respectively. There's a touch more nuance in that you DO go back and forth between Starfall and Wrath (unless >3 or 5, forget which, targets, at which point you apply Sunfire, use Starsurge on CD, and spam Starfall regardless of whether in Solar or Lunar), which would be like giving us a reason to cast Holy single-target in FFXIV, but in terms of overall kits...there' PRETTY close to parity.
Balance, that is. Which is slightly less DPS than Feral, but doesn't require melee, which makes Balance (from what I was reading) arguably preferred in raids, since a Resto Druid in Cat form in melee range with the melee blob can still be targeted by boss attacks that prefer ranged/caster/healers. Feral, on the other hand, is more useful in Mythics where, according to IcyVeins, anyway, a 0 DPS Druid vs a full uptime Feral marks a 10% contribution to the 5 man party's overall damage (Feral OR Balance in 10-25 mans contributes a far smaller percentage, making the choice much less significant and Balance possibly preferred for raids)
In the case of Feral, you retain Wrath, Starfire, and Sunfire, but add in (I won't remember the names, I was never a fan of Feral outside of jumping into Cat form in Battlegrounds like Alteric Valley so I could stealth around the map while still being a healer - something that I THINK is unique to WoW as I'm not aware of any other game where healers could use stealth!) another upkeep DoT, a basic combo builder strike, and two combo finishers, one being a DoT that you prefer (for damage) with the other being a direct damage that can be used instead if the target is close to dying. Oh and an AOE spamable (Swipe) in place of Balance having Starfall. You technically also have the combo spender that can stun, but it can only be used from out of combat and WHM has Repose anyway.
So compared to WHM, Feral has Swipe instead of Starfall for Holy, a DoT OR direct damage combo spender (imagine if WHM had a second Blood Lily spender that was a DoT instead of Misery - and for the sake of argument here, Misery would be equivalent to Feral's combo spender that does direct damage), a damage attack to build combo points (we can ARGUABLY equate this with Lilies though - they don't do damage but build "combo points" towards Misery, but they AREN'T spamable while Shred is), and an extra DoT from Rip, I believe it is. Oh, and still has Sunfire, though here we'd probably just call that Assize in this case.
So Feral has (if we hand-wave Shred for Solace/Rapture and keep Wrath as Glare and Dia for Moonfire, though I'm not sure if you'd use Wrath at all with this build outside of disengage situations, if those exist in WoW..?) roughly two extra abilities, largely in the form of an extra DoT (Rip) and a DoT combo point spender? If we view Solace/Rapture as Shred OR Rip and Glare as the other (handwaving Wrath away as "you don't use this if you're Feral aspected), then they're arguably the same number of overall damage buttons. If we can get over the fact that Solace/Rapture don't do damage outright themselves...but ARE part of the WHM rotation, even if healing isn't needed, for MP management and that Misery is a slight DPS gain, namely if used in burst windows. So including them as "dps buttons" actually IS valid, even if it seems like it shouldn't be. But again, if we set that aside, we'd say Feral has roughly 2 more damage buttons than WHM?
Though again, I'm not sure how Feral plays here, so I don't know if you're power shifting to cast several Wraths as part of your normal rotation or if we can just substitute Shred for Wrath as our "Glarespam" in this case. I feel like that's more likely, as what I read seemed to indicate Wrath was kind of your "lowest priority/last ditch DPS option" when you're using Feral affinity that you use when you can't be in Cat form for some reason. I'm also not sure if you can cast in Cat form or not? I vaguely remember some Talent or Glyph that let Guardians use Moonfire and Rejuvination in Bear form, but I don't know if that is still in the game or is in the game for Resto Druids?
I didn't even look at Guardian as IcyVeins didn't mention it...but you kind of note that and I think we agree it's probably NOT a popular option in general and we can set it aside.
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So the shorter version:
Guardian - Less buttons than WHM like as not, but who cares?
Balance - ROUGHLY the same number of buttons as WHM, plays SORT of the same as WHM, but with a little more nuance (e.g. if you used Holy some in single target and used Wrath some in SMALL pack multi-target), and with the abilities you use less often (Starsurge, Sunfire) having shorter CDs than WHM's rough equivalents, meaning you press those buttons somewhat more frequently than WHM presses its (Assize, Misery)
Feral - ROUGHLY the 1-2 more damage buttons, though it seems you press them more frequently as well, do a bit more damage but at the cost of doing much less when unable to be in melee, and have some fun side mechanics with stealth gameplay...but that doesn't really translate into FFXIV's combat system, dungeon system, PvP system (even NIN stealth is only active for, what, 10 secs in PvP?), or exploration content. Sadly, as I rather enjoy that.
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So yeah, I did actually go and read up on it since it has been a while and I wanted to make sure what I was saying was still somewhat accurate - and it was completely so 3-4 years ago - and it still seems to be LARGELY accurate today, again with caveats.
The NICE things are:
1) Resto Druids have the option to go with one or the other - which sadly wouldn't work in FFXIV's combat system (as Mr Happy noted recently, the idea of a "melee healer" doesn't work in FFXIV since it competes for uptime against melee DPSers when dealing with Savage/Ultimate mechanics) - if people want slightly more complexity or slightly less.
2) Resto Druids use more of their damage kit more frequently because the CD/gating (combo points) happens faster than WHM's equivalents (60 seconds for Misery, 45 seconds for Assize)
3) Resto Druids actually use their HEALING KIT a lot more, too, since WoW forces a good deal more healing than FFXIV does.
3) There's a BIT more interaction with their damage kits than with WHM, where the only real interaction is between Rapture/Solace and Misery, and that you can use Presence of Mind with things (not sure Resto Druids have a PoM equivalent, but I THINK they do, even if it's more used a healing tool - that thing that just shoots off a bunch of spells all at once. Which...admittedly sounds WAY more badass/fun, though a lot of those are heals. Magic explosion!!

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Holistically, I don't see them as being ALL that different, as I presented above - the Balance interactions don't really change things other than you cast your AOE spam nuke in single target and in FFXIV you do not; that is, Starsurge buffs don't really CHANGE your rotation, it makes slightly bigger numbers for continuing the same rotation - and Feral nudges you into Melee and gives you an extra two DoTs (one as a combo point finisher) and leverages the combo point system, which Balance does not (WHM has Lilies in both cases as a near equivalent to this, but it's more of a side gauge due to the Lily refresh being once ever 20 sec rather than Feral being able to generate combo points with Rip and Shred)
I can see Resto Druid being a bit more active since CDs are lower, but I'm also not sure how many more heals you're having to cast in WoW, since WoW doesn't have oGCD equivalents. That is, you're HAVING to interrupt your Glarespam to cast Medica 2, refresh Regen on the tank, cast Cure that has a HoT attacked for spot healing, etc. You can't just Tetra, Assize, Bene, Benison, Asylum weave and continue casting damage spells unabated, yeah?
And, again: Stun = Repose, WHM has this, it's just not used in FFXIV (and it's not used against in boss fights in WoW, either, since you can't stealth in boss fights)