I honestly think removing all direct damage buff that are party wide would be interresting to explore.
Have buffs be more indirect helps such has reduced cooldown, cast times, increased mp regen, movement speed etc.

Bard could still keep its cyclic "2% damage increase" during the songs etc. And if this all leads to job rotations spreading further again and being more varied that could make something interresting for dancer where as its dance flourishes are like minute or two minute, but some other dps are 3 minutes, you'd benefit the team more when knowing when to swap dance partner so you maximise everyone's DPS one at a time. That'd be quite a high skill ceiling on dancer all of a sudden. Could be fun, I think.