so a 15% damage buff is going to stop ret being the most fragile and easy to control melee whose entire toolkit isn't replicated by their healer spec?
when arms warriors were full retard in 5.0 they didn't get brought to rbgs, because they were melee and melee are fundamentally less valuable in rbgs because of their positional requirements. the two melee that are brought are brought for very specific gimmicks, rogue for smoke bomb, and dks for grip.
even if they gave ret a 100% buff on sword of light they wouldn't get bought because they still bring no real utility that can't be replicated by holy.
elemental is fine for rbgs, they have some of the scariest burst in the game and unlike ret they have utility that can't be replicated by resto from their knockback.