I beg to differ, if I can choose between two good but boring classes and three "bad" but quirky and interesting ones, I'd rather have the interesting ones regardless of if they are "balanced" or not. (If everybody is special then nobody really is)
Why don't we just have five quirky, interesting, and balanced classes? That seems like the ideal state to me.
You really are presuming a correlation between balanced and boring that simply isn't true. Plenty of games have pulled off both balanced and interesting at the same time. Heck, even 3.5E has plenty of classes that fit both criteria. Most of my favorite classes from that edition also tended to be the well-balanced ones. It is the boring classes that tend to be the broken ones (either too weak or too strong).
An ideal game is full of options that are both fun and well-balanced. In fact, I think that fun and interesting requires an balance in order to exist. The elements necessary to create a balanced class tend to make the class more fun and quirky.