The last thing the game needs right now is combo consolidation. The reason VPR has it is probably due to flavor and to enhance its basic GCD game play, as otherwise the job would've been left with 6 GCDs if they were not on the same button, making it as simple as their AoE combo.

Consolidating them on that job let them add the last 2 positionals for single target because they thought that having 8 buttons in your hotbars just for a basic combo was probably too much, even if the effect is having a job with empty hotbars.

Jobs are too simplified right now. Combo consolidation would only make sense if they were more complex and job design required it. As it stands, it doesn't. Doing PvP rotations in PvE would be awful.