Depends on how you look at it. SMN technically has 12 damage related buttons (15 if you count the AOE variants as separate, even though they map 1:1 to the single target and most of its abilities are AOE), and that's counting Searing Light, Ruin 2, Energy Drain, Fester, Bahamut, and Enkindle Bahamut, but is almost always called a "2 button rotation"/"same 2 buttons over and over". You can technically point out that several of these buttons pull double duty, with Ruin 3 taking on a different ability under DWT and FBT, and with Gemshine and Astral Flow having 3 different forms each for a total of 6 different abilities. But don't say that in the DPS forum... needless to say, most people aren't counting those as "rotation". The "rotation" is generally going to be considered as only having 3 buttons, Ruin 3, Gemshine, and Astral Flow. No other button on their bars is hit more than twice in a 60 second time period (Fester is hit ONLY twice), and Ruin 3 itself isn't hit more than once (unless you died), it's the hot-swap with Astral Impulse/Fountain of Fire. SMN's rotation is weird since the buttons change how you use them, but people constantly insist it's only a 2 button rotation.
MCH has 7 GCD buttons that are vaguely part of its rotation. Heated Split, Slug, and Clean Shot, Drill, Chainsaw, Air Anchor, and Heat Blast. Its AOE drops the 1-2-3 for Scattershot, Drill for Bio Blaster, Chainsaw for itself, Auto-Crossbow for Heat Blast, and Air Anchor is dependent on how many enemies (enough enemies and it's a DPS loss vs Scattergun). Flamethrower is an oGCD technically. Even if we count the oGCDs, we're at 14 for single target, with only 4 more for AOE which merely replace the 1-2- combo, Drill, Heated Shot, and Flamethrower is kind of its own thing. MCH's single target rotation is 3 buttons in a combo, 1 button based on a gauge, and 3 buttons based on their own CDs.
RDM has 8 single target, 4 AOE GCD hotkeys. If we add in Holy/Flare/Scorch/Resolution (the latter two being pressing the same button twice, akin to PLD's Requiescat combo), that brings us up to only 12 for single target and 8 for AOE. But these are more situational/proc buttons (change based on context, not wholly distinct). It's sort of like asking if Repost and Enchanted Repost are the same ability or not. Still, the core casting rotation is 5 GCDs. There are 6 oGCDs if you include Swiftcast (RDM can since it doesn't have to save it for Raise) with Contre Sixte, Fleche, Manafication, Embolden, and Acceleration. Technically you have Reprise as well, I guess. Oh, and I suppose you could count the movement oGCDs, though two of them share a CD. RDM's rotation is weird since there are a total of 7 buttons you only use once per full rotation cycle (the melee combo and following magic combo, of which you only use one of Holy/Flare per combo), but three of those share a hotbar and elemental distribution. The thing is, unlike SMN (to the people that dislike it), these feel distinct somehow and their specific rotational order somehow makes people think of something more than with SMN. That is, they are never counted as "just 1-2" like SMN's rotation is.
DNC could probably be fit in here as well, considering how people talk about it, but I don't use it to know that one. I'll have to level it and look through what GCDs it has and how its rotation works someday.
WHM, strictly speaking, already has 5 GCDs in its damage rotation; Glare, Dia, Afflatus Solace, Rapture, and Misery, with two damage related oGCDs, Presence of Mind and Assize. Debateably Swiftcast and Thin Air. An optimal WHM should be keeping Thin Air charges rolling by using up the second charge at any given time on a Glare/Dia...no one does this, but optimal play technically would be doing this since under optimal play conditions, you aren't using Raise, and definitely not hardcasting Raise.
Some Jobs are fantastic at compressing lots of abilities into a few buttons, with SMN and RDM being big examples of it, but so does PLD (while still having button bloat somehow...) and GNB with Continuation and Gnashing Fang both. Are those separate abilities as far as rotation? Technically yes, but...whether people classify them as such is kind of hit and miss. While way too many people call all of Gemshine and Astral Flow the same two buttons, almost no one does that of Verholy/Flare/Scorch/Resolution. But on the other hand, people kind of ignore the non-Enchanted 1-2-3 melee combo exists as the only time it's EVER logical to use it is if you're Verraising to the point of having no MP at which point it becomes technically more DPS than standing there doing nothing while waiting for a MP tick or two for another Jolt.
So really it more comes down to how you say it, and there's no good way. "Tank rotation" - is that the 1-2-3 -4, or is that the oGCDs as well? Does Gnashing Fang/Continuation count, or is that a side thing? Does Requiescat count as 4 buttons or 1? Which Tank are we talking about? If we count all the abilities (e.g. all Gnashing Fang and Continuation), GNB probably has more than some DPS Jobs. 1-2-3, Gnashing 1-2-3, Continuation 1-2-3, Burst Strike + its continuation, Double Down, Sonic thingy, with oGCDs Burst Strike, Circle of Scorn (it's totally Circle of Scorn...), Bloodfest, and Fight or Flight (okay, fine, No Mercy). Oh, and Lightning Shot. Then we also have to remember the AOE 1-2 and spender. That's a total of 18 abilities, 14 if we don't count oGCDs, which is higher than SMN even WITH counting its oGCDs.
It's more to say "If you'd like more damage buttons, do you want something like a full on DPS rotation, or do you want something less?" But again, I was adapting the questions you gave me.
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PLD and SMN are going to be interesting since they're both likely to be VERY bimodal. Some people loving them and others hating them and wanting their old versions back. I'd say SMN more since the changes were more drastic, but PLD's changes are also more recent...