BBC News has an interesting article about Comic Sans hatred:
...why, more than any other font, has Comic Sans inspired so much revulsion?
Partly because its ubiquity has led to such misuse (or at least to uses far beyond its original intentions). And partly because it is so irritably simple, so apparently written by a small child. Helvetica is everywhere and simple too, but it usually has the air of modern Swiss sophistication about it, or at least corporate authority. Comic Sans just smirks at you, and begs to be printed in multiple colours.
Perhaps the most comic thing about Comic Sans is that it was never designed as a font for common use. It was intended merely as a perfect solution to a small corporate problem.
The article goes on to name the creator of Comic Sans, who does not apparently regret creating his Frankenstein's Monster of a font.