Before you say "well... you're using fully-buffed stuff to do that, so it's not a fair comparison", I'd like to point out that in order to cast those 12 full-power incinerates, you need to also be kitted out to the near-max for destruction with low to zero magicka cost. So -- enchanted out, just as the warrior types... just in a different way.
Destruction is at most 1/12 the power of melee (actually that's being very conservative, it's really a lot less)... and don't even get me started on backstabbing vs. destruction.

But having said all that, I still love playing my mages. It's not like they are terrible -- quite the opposite, actually.
-Loth
In general, it's very easy to make something OP in Skyrim, what would your solution to Destruction be? Would Scaling suffice?

Best of luck in your continuing adventures.