Fauchard1520
Adventurer
Overspecialization is something you do with NPCs imho. Often they are going to be used for a specific occasion (but not always), which may or may not involve combat.
In my experience, the true one trick pony enthusiasts are fairly new to gaming. They're just getting into the fun of character builds, and haven't had the chance to sit down and run a game. Because you're right: I think that's where you get a lot of the wackiness out of your system.