I've played mobile ranged DDs (lock, hunter) as well as melees (monk, DK) before I quit some months ago and both types are fun. What I can't stand is the immobilty of a shadow priest for example (if he doesn't have a lot of targets for multi dotting nearby). If this is their vision how WoW as a caster is meant to be, than I agree: WoW isn't for me any more.
There are plenty of knobs to turn im my opinion regarding the balance between ranged and melee damage... but forcing casters into turret mode again like it's still 1998 is not the one they should be thinking about.