Too bad the show doesn't portray any intelligent person as normal as those you receive "support" from.
In the scientific crowds I have been a part of, Leonard is on par with the more "normal" people I have known. He still has quite a few geeky quirks, but overall he can blend in as well as most geeky guys can. He has a hard time with some of Penny's brain dead friends, especially when watching sports, but overall he seems pretty normal to me.
Leonard has always struck me as that one normal guy which is quite common in many geeky cliches. They can't have too many of their characters be well balanced or else why would the show be fun to watch?
From another angle, take a look at Two and a Half Men. You have a womanizing morally bankrupt millionaire, an incompetent brother, and a brain dead son. If I were a millionaire playboy, divorced middle aged man with career problems, or a teenager who struggled in school, I wouldn't want any of those characters to represent me. While each of them may get laid more than the character on BBT, I wouldn't consider any of them to be "normal" either. Abnormal people simply make for great television.