I'm not talking just cash shop costumes here. I'm saying all costumes. Unless you really do want to refarm all those very rare and elusive costumes on your alts again.
As an example, Destiny cosmetics are account bound, and it is a vastly superior system. Bungie, being actually somewhat competent and attentive of their players, realized the grind was burning players out and just did away with bullshit cosmetic grind in a single sweep.
Premium is still junk. The only good thing about premium is the wardrobe which shouldn't even be locked to premium. That's a quality