Yes, it would need to be something meaningful to the job and not redundant with the rest of the model. That's also probably why not every job would use it anyway. That's also why I stopped at 3 jobs even though I considered more without finding anything suitable (that, and I don't have 3 years of expansion development to pour into the idea tbh). On SAM I considered the - very - wild idea to get inspiration from pvp and introduce "kaiten ready" which you get after dashing, except here you'd get it when enemies die. In pvp this transforms the basic single target combo into its AoE variant with added special effects (bind, aoe potency, hp leech). Well let's say in pve you kill mobs with Tenka (or idk what), then it gives you a free 1 stack meikyo (activated automatically). Which brings the next Tenka sooner, etc etc.

Anyway, I have the feeling that the secret ingredient of the current pvp sauce lies in all the secondary effects that come attached to a lot of abilities there. This makes abilities not only more versatile and multipurpose, but it also triggers other effects that can be used cleverly.