Barbershop : well, yeah, why not…
Transmog : no, because it’s a cool thing to instantly indentify rare and valuable gear on people when they have it.
Dual spec : no, because if you do this, you reduce the value of gold. And if you reduce the value of gold, you change the game in a big big way !
- you reduce the interest in gaining gold through playing
- you reduce the utility of professions and trading (a main feature of a mmo !)
- you reduce the pleasure to gain the mount (especially the epic one)