Yes because
this is so much better...
http://i.imgur.com/TGHg4jW.png
I'd just
love to be the healer for that, as the entire alliance's dps go down on the first cleave from the boss.
That sure does sound fun!
That's not even touching problems like mechanics that target DPS with ground target attacks now getting placed on top of your tanks, requiring tanks to move bosses more often when a lot of fights require the tanks to keep the boss in a specific spot. And other incredibly numerous other problems that come with a DPS job designed to attack from the front, all for what? When you could just make that job a tank.