That's what glamours are for? Just because caster/healer costumes are the same in each tier, doesn't mean you have to visibly wear those matching sets.
That would make sense if they wanted to cut down on the number of sets. They do already share Aiming accessories.
Although if they don't plan on cutting down on the number of sets, I'd like to see the accessories renamed to reflect that they cover multiple sets, like the Slaying ones that don't correspond to a single set but are shared by the other two melee DPSes.
