Recently it was announced that experience would be increased for certain types of mobs. Now inherent with any change is...well complaints. Moorgard clears up the reasoning behind the new experience changes.

As far as raiders go, they'll see more XP from killing epics, but the goal isn't to make it efficient to grind for XP on epic targets. This change is more to offset the fact that raid XP is pretty low and debt can build up pretty fast with all those deaths. Again, not everyone who raids is at level 70 with 50 achievements, and that's the kind of player that will see the most benefit from these changes.

Read his post here.