I don't think we have a word for people who try to make powerful characters but end up with glaring weaknesses in the process. --->"Hey I can do 500 damage per round at level 10, but I have a -5 for my will save." <---Most people who optimize do not want to be that guy, and yes that is hyperbole, so don't take it literally.
That term is "Evil Lincoln".
Well not really, but I am guilty of one-sided characters. I don't even mind their obvious weaknesses, I think it makes them more fun to play.
Actually a min/maxer is someone who takes the maximum amount of weaknesses he can have with the minimum impact on his character's power or survivability. The term was coined for point buy systems, but it has exploded in popularity and now is sometimes used synonymously with power gamer or optimizer.
Edit: A good example is dumping a stat you will not need to 7.
The thing is. That 7 or possibly 5 could be what gets you killed, and possibly the rest of the team.
Poison or ability drains are easily the kryptonite to those min maxers.