I don't know, maybe because mages are more tanky than hunter, have more cc on different school, more mobility, a better offensive dispel since the hunter nerf, have perhaps less burst damage, but more than most of others casters and all instant, and mages players tend to be more pretentious about their class. Instead of spaming icelance like during MoP and pretending to cast something at the end of the game when someone is dead (Frostbolt was like 1% of the total damage during MoP), it's just 2 icenova with a comet storm.
It's like saying "Damn, the hpal's NS is overpowered" when you're playing a resto druid, do you realize how stupid it would be?
Both of these classes, hunters, mages are like you said : "braindead". The difference is that mage did not wait until MoP to be "overpowered". They had some weaknesses during some seasons, but never replacable or bad.
No jealous. \o/