I would remove party-wide damage and de facto damage buffs across all classes.

Then, the two minute meta having been eliminated, retool jobs to focus on buffing themselves or single partners (kind of how a lot of skills work already) and otherwise create more reactive/improvisational gameplay loops instead of a railroaded rotation.

If any party-wide buffers did exist, I would make them expressly be able to keep up their buffs for most of the fight instead of a brief window, with one of their primary mini games being the maintenance of the buffs.

Conservatively though I would err on the side of no party buffs. GW2 went that direction and now every support class feels the same, expected to proceed all the buffs all the time with no flavorful differentiation. I suppose in theory you could balance say, a haste-support to be roughly as effective as a power-support with number tweaking and a limitation on how many supports per party, but players will somehow ruin it with optimization anyway. MMOs are a wonderful demonstration of how individual ambition en masse--in this case, most players prioritizing grind efficiency over actually enjoying the feel of the game--just destroys all things good and beautiful in the world.