Some examples of DPS that are not punished are warlocks, hunters, and elemental shamans. All three of these lose close to no DPS when moving. This would be fine if other specs such as shadow or balance didn't lose so much DPS on the move. Mages also face DPS loss when moving but they have a plethora of positioning tools (blink, blazing speed) and can fill the GCDs with instant casts.
Personally, I feel that instead of classes being brought up to warlock/hunter/shaman level of movement DPS, those classes should be brought back in line. The drawback of a caster is that they can't keep DPS up on the move. These classes don't have that drawback.
An alternative is giving the other classes better movement DPS tools. While I feel it is an abomination to DPS on the move so efficiently, certain classes shouldn't have such a clear advantage to others.
Movement DPS for caster will probably be nerfed severely come 6.0 but that is a long time to wait and fixes should be made now to balance out this disparity.