As someone who had a Rank 11 title back from Vanilla, it rather sucked, but it did happen exactly how I predicted it would happen: people would use the transmogs for 2-3 days, get bored of it, and go back to their normal stuff. The sets themselves aren't good. What made them good was the rarity.
All it really did was make sure the veterans who actually earned their sets in vanilla detracted away from them.