We are approaching a button bloat problem that can be solved

[Momo_Kozuki]

I truly don’t get why Square Enix hasn’t changed more 1-2-3 combos to share single buttons; they already had that in older PvP job design, and Gunbreaker already had this quality-of-life update with regards to a higher-level combo that’s done with Continuation, so why stop there? Seems a lot better than removing entire actions like a certain Samurai action that lots of players liked to use.

My guess, but they don't do it cuz it is not the time now. I think they have a certain number of button in mind, which has not yet reached in 6.0. Maybe in 7.0 or 8.0, they will do it when more buttons will be added.