As an Endgame Bard right now (jokin, i still need to do ifrit in hard mode, just hit 50 and finish main quest), i can say that: SINGING. IS. USEFUL. Mages gonna love you. Period. Having the Whm/Sch who can regen faster his mana, means he can heal more. And you'll need a lot of healing, expect a lot, a LOT of AoE, and you can't dodge all. So... Sing your songs, fellow bards, and make your job not only limited by damagin the bosses.

...Also, btw, we are the master of criticals. Nobody do as much critical as we do. Believe me.