Now that's something I am not knowledgeable enough about to have detailed discussions about, sadly.
Definitely there is a need to spread the buffs more, and I do think more variety among them would also be nice. Dedicated supports can keep straight % increase sure, but I just hope we move into a design space that isn't as cleanly aligned as it is now. 'cause you don't really "need" to work together to align stuff outside of very complex fights where mechanics force a delay. If it comes to a "Ok in this party we play with a dragoon so for them better hold on the buff for a bit so they can build ressources and get the most value out of it." vs "Alright we have a samurai there, just gotta wait a few GCD and then let him let all hell loose" that'd be nice I think.