I voted no.
I think it all depends of the edition and the circumstances.
Fighter vs. Wizard in an arena
If this is 1e, Fighters are very gear dependent, and gear doesn't really matter for the wizard. So in a high gear situation, the fighter can be very powerful. In a low gear situation, the wizard might shine.
etc., etc.
Do I think that spell casters are awesome? Absolutely. They are fantastic.
But fighters, rogues, etc. have their uses as well.
D&D (before 4e) is not as balanced as WoW, but its not as nerfed as 4e either.
In classic AD&D, fighters have better HP and better AC than wizards. A wizard could die in a suprise round to an attack the fighter would barely notice.
On the other hand, the wizard can do amazing things with Wish and other spells.