Just to start, I want to say I'm generally on the same side as you on this issue. I like the current SMN and I think the additions in HW was the perfect direction for it (for me anyway). I never wanted an emphasis on pet micromanagement, and I don't think FF summons have ever been about that anyway (minus 11).
But I think you're mistaken on how SMN was before. It was never that focused on the pet. People complaining now about that, they complained back then too. The 60 rotation only filled out the down time of the 60 one and added an aoe (Tri-disaster being more of a QoL change). The downtime being waiting for aetherflow after using up all your stacks.
Any min-maxing the pet back then should be done now too. It was only focused on back then because SMN had less to do and the pet's damage was a bigger percent of our overall damage since our rotation has less skills. But the bare-bones pet management system now wasn't any more involved at 50.
And though SMN sucked in Final Coil, why is that the only thing people remember? During the First and Second, SMN was the best single target ranged dps. A good SMN could compete with a MNK in terms of raw dps while they also brought more utility like a battle rez (while not being the healer).
This also brings up the next point. I wouldn't hold a ton of weight in SMN as an aoe class being an important niche. Precisely because BLM was once king of all AoE for so long, no one would believe it is the way it is now. SMN being great at single target meant that indeed the casters were balanced like that before but since it was flipped, I don't think it's something to hold on to.
Some jobs will always have better AoE but being an AOE class is not a thing. Luckily, SMN's single target is still good and doesn't suffer for it.
Lastly, let's be real about popularity. SMN went from the least flashy class to what might be the most flashy. That, I firmly believe, accounts for most of the rise in popularity. Viability doesn't always lead to popularity. MNK was the least popular in most of ARR while being the highest dps.
The other reason is a lot of BLM's switched because people like AoE and they went to the new king of AoE. Those same people will switch again if SMN's AoE isn't better than BLM or RDM after the scaling, new skills and general damage adjustments at 70. There's really no guarantees it will be.
(Did I mention MNK went from laughable-just-give-up AoE to the best melee AoE job with one skill going into 60. Do not trust SE to let you keep your niche.)
The only thing I would like with SMN is for the egi's to show up with some of the abilities. It could even just be the new skills, rather than redoing the old ones. No pet management, just more visuals to show mastery over the egi's.
I wouldn't like the Egi to look too much like the originals just because of the lore. It's already a little handwavey how they justified SMN while making the primals inherently destructive presences (not just to our enemies). If they actually looked like mini-versions, it would be too much imo.
My ideal SMN would not be dot based. It would be a pure nuking class. It would not have even have pet though it might have skills to summon an uncontrollable ones temporarily (though the current pet isn't horrible). All of its skills would have a visual that includes the Egi appearing to do the damage. Similar to the Wildfire animation where you see the machine appear next to the mob and it blows fire one it.
None of that will happen but that's what I would do. The development of Dreadwyrm is a fine path too and I would keep that with mine as well. I think SMN has only improved since ARR.