I think the aim should be for “both”
back in the day with set bonuses on armor, you didn’t NEED the set bonus for your class to feel “good” but the set bonuses could certainly make your class feel “better” (to the point where it wasn’t uncommon for people to mix and match bonuses from multiple raid tiers)
however set bonuses are rather minor changes, in order to have the sort of substantial differences they want I can “understand” by blizz is going the route that they are, after all its much easier to balance around the “end result” rather than needing to make sure things are balanced around the end result AND the comparatively short period of time till players actually get there.