Ulth, I don't play Warrior ever so I held my opinion back at first but since you asked..

A fulltimeable (aside from dispels soon after use) 60% buff to attack.. Really? That does seem obnoxiously overpowered. Non-Idris GEO's attack buff isn't even that powerful. You want this on Warcry.. would you have it be as powerful for all party members? That makes warrior simply mandatory in any melee setup.

Tanks and Healers are mandatory but PLD and WHM are not, it could be RUN and SCH or in certain content RDM and NIN. GEO is mandatory because GEO is a modern job designed around modern mechanics--cor needs a buff and bard needs an overhaul. A buffer being mandatory is fine, one particular buffer being mandatory is stupid.

Your design would make warrior mandatory.

BLU is the closest thing to a mandatory melee right now because it does the best at overcoming the crappy situation all melee are in. The evasion on some of these bosses man.. it's obscene. The aoe-damage they do is insane. I don't care about single-target damage. I'm a tank, hit me harder please.

Scholars are mandatory in setups not involving melee. If you're relying on melee skillchaining, scholars and BLMs are generally interchangeable (BLM doesn't have Helix II, useful JA's, the ability to SC if the melee can't, SCH doesn't have Death, native MAB (storms help), etc).