To me jobs being different means you have to scrap the 2 minute burst window.
Make buff jobs provide an enormous bonus to the party.
The Parser devs could do a lot to help here. All DPS that is created by a support buff should belong to the buff job, not the player who's buffed. Tough (one of them has to loose out)
That buff bonus needs to be large enough to make filling their rotation with sub optimal to sync with the 1:30 rotation of the best Mele SAM for one party, or the 2:30 rotation of the best DPS SMN the next party... worth while. Or least much-of-a-muchness, averaging out, because they'll buff two jobs this time, and next time they'll buff one.

And I'll say again... all DPS thanks to buffs needs to belong in the parsers to the support job, not the job they are are buffing. Otherwise we will have the usual complaints that they are underperforming, when they are not.

Include in this that maybe MNK for example needs to spend their Buff on the SAM and not on themselves. Or spend it on two ranged instead of themselves.

Again, buffs need to belong to the supporting job, not be credited to the job they are buffing.
Just find a way for all jobs of signalling in their status indicators that they are probably starting their burst, and then leave using that to the skill off the supporting job.

Really try to make every job have a different rotation period.

I'm probably not going to be convinced otherwise, as the maths to model/prove these dynamic relationships is complicated, and I wouldn't care to look into it, so I'm going to go with my intutive analysis.