Why doesn't pve have pvp combo structure?

[Achantion]

There's definitely room for button consolidation, but simply turning every combo into one button isn't the best way to do this. Many jobs have skills that are mutually exclusive, you can't use one while the other is available, or some skills simply become redundant in the presence of others.

That is the real issue, not button merging.

BLM: Combine Ley Lines and Between the Lines. Have B2 upgrade into Freeze and F2 upgrade into Flare.
NIN: Combine Dream within a Dream and Assassinate.
SAM: Combine Meditation and Shoha. Upgrade Shinten into Seigan when under Merciful Eyes.
DRG: Combine Fang and Claw with Wheeling Thrust. Delete Piercing Talon.
PLD: Combine Requiescat with Confiteor. Combine the effects of Intervention and Cover, or simply buff one and remove the other.
GNB: Probably would make the Gnashing Fang combo here a 1 button combo, the same as Continuation. So that you simply alternate between the two just like MCH's burst phase.

Most of these are perfect examples of what I'm aiming at. Make a button have a mechanic.

Yet, these are generally all things you do in between your basic combo's. I would love to see the same mind set applied to more varied basic ability design. Make certain combo's reactive, require a pre-requisite, lower damage but faster GCD (and visa versa), etc.. Button consolidation wouldn't be an issue with more varied ability design.

I'm going to stress again that button removal isn't the goal. For each button removed a new one should come in it's place, but, 1-2-3 combo's are just an artificial way to pad the number of buttons a job has access too.

Sure some classes in their current design might need a tiny redesign, but as NIN's Shadow Fang has proven, there are easy cop-outs to achieve this.