Crafted and dungeon gear is shared by roles (generally...)

Tanks share gear, Healers share gear, Casters share gear. They have the same primary and defense stats, so they can share dungeon loot. Yeah, BRD, DRG and MNK all have unique gear after a certain point (post-50 really, though there is some DRG/tank gear early on) but that's because they are different from each other (DRG and MNK may both be STR-based, but they have different defense needs. And BRD are the only DEX-users for now)

I do expect the Musketeer to be DEX-based and use the same dungeon gear as BRD, and classes to use MNK and DRG gear to be added eventually too (probably based off GLA and MAR though, rather than LNC and PLG)