I'd agree if you said that enmity combos were unavoidable in ARR, given that you needed them for establishing snap aggro on adds (which the likes of Equilibrium later trivialized). I think that this was actually fairly interesting, as you had to be on a particular combo step during phase changes to be ready to SS > BB the moment the add dropped. But there were enough enmity tools from Heavensward onward that they weren't completely mandatory, especially with a NIN present. The only DPS job that didn't have tools to let you comfortably retain your enmity lead once established was MNK, and they tended to be less common in DRK groups due to the DK/Del overlap. And if you were going to have a tank use an enmity combo, it was going to be WAR because Butchers' Block carried the potency advantage. By Stormblood they were pretty much irrelevant due to the introduction of Shirk.

If it was mainly a visual issue, then that's fine, but there are better ways of doing it, and we'd also have glamour options for moves, similar to Warcraft's glyph system. You'd also wouldn't see people so resistant to PvP's approach of merging down a combo to a single button press (any predictions on whether GNB's continuation combo is going to go this route in Endwalker? #notIR) People are obsessed with this idea that having more combos automatically translates into more job complexity, when the actual decision making is the part that really engages your brain.

The thing with non-standard recast GCDs is that they pop up at different points in your standard combo. So it's sometimes 1-2-3-4, sometimes 1-4-2-3, and so on. That's a bit more interesting than your standard combo in terms of varying up the button presses, as long as the recast time is sufficiently short (i.e. once every 4, 5, or 7 GCDs). These sorts of actions are just one step below DoT management in complexity. It's a bit like having a Scourge button that doesn't let you press it too early, and gives you a visual indication on when to use it by lighting back up again. If I was creating a job from scratch, instead of giving it three combos, I'd give it one combo with two non-standard recast GCDs that intersect with your combo in different ways (say a multiple of 5 and a multiple of 7). It's the same number of buttons and actions, but it's much more varied (5-4-1-2-3-1-2-4-5-1-2-3-1-4-2-3-5-1-2-4-3-1-2-3-5-4 instead of 1-2-3-1-2-4-1-2-5).