I don't know about reducing to PvP levels but PvE rotations absolutely need a reduction in button bloat.

I think the best place to start is putting abilities that are mutually exclusive on the same button.

Like...Why does a Black Mage have Fire IV and Blizzard IV on separate buttons when it is literally impossible to use one in any situation where you can use the other?

Why, for Summoners, is Enkindle Bahamut/Whatever on a separate button from Summon Bahamut/Whatever when you obviously cannot enkindle what isn't summoned?

Things like that. Same number of abilities, fewer buttons.