Button consolidation should be a thing - not even as an optional thing, in my eyes. But it hinges on a key point: that our current combos are expanded with choice.

If the combos contained within the consolidated buttons are the same 1-2-3 steps ad infinitum, then PvE content will become boring. For such a change to function, players must be given an active choice when moving through the combo. Ideally, there would be priority and situational decisions to make, and/or loops within the combo that doesn't involve the combo starter. Such combo design would in turn also require a change in how PvE encounters are designed. With more space created on hotbars, there's opportunity to bring in oGCD and more niche actions that can find their place in interesting encounters.

That being said, the above change runs counter to a lot of what SQEX want from PvE. Despite wanting it, I can't see it happening.

Oh and digressing a bit: why the hell is Dream within a Dream and Assassinate not consolidated into a single combo button now? They did it for Verflare and Verholy. Do it for NIN!