The mage simply rocks.
I throw down an Affliction Hex, then Storm of the Century and.....
The power is totally corrupting. Once you have it--its hard to give it up.
You cackle and laugh and whistle in amazement. (It's hard though to be too awesome when your own robe is on fire)
Enemies that were tough for a warrior and impossible for a rogue are just no problem at all.
The mage just plain obliterates mobs. So powerful, yet so flexible.
No other character in the game even comes close. It's waaayy overbalanced.
Now if my mage could only pick locks!
I'm sure I could find some other use for Princess Leliana....