Why do some movies portray scientists as geeks?

Image via WikipediaI was watching my movie pick, Deja Vu, and noticed the scientists who made a special scientific discovery of seeing into the past, were portrayed as nerds, not your everyday person who functions normally in life. This got me thinking about more movies in this genre and how often the smart characters are geeky looking or acting. I could make a long list of movies, like The Day After Tomorrow, The Core, Spider-Man, The Fly, and more that escape me at the moment. Television is not exempt from this stereotype with one example being the TV series The Big Bang Theory, which is not Sci Fi, but depicts these physicists as complete nerds not really capable of functioning in daily life. Even in Jurassic Park, Jeff Goldblum as a brilliant mathematician was seen as an oddity.
I wonder why this stereotype has proliferated in Hollywood? I have known chemists, physicists, and mathematics professors who are anything but nerds, geeks, or unable to function in the "real" world. Some of these professionals I have known have been downright hunky or sexy. Maybe my high school chem teacher was a bit odd, but I believe he did it to fit into the stereotype and keep us interested in what he was saying, he was more like a clown than anything else.
I have noticed the trend is starting to end a bit with certain Sci Fi shows like Star Trek, StarGate, and even Eureka where the impression I get is the Sheriff is the geek and not the scientists. In the theatre, Contact, The Alien series, and X-Men all have the intelligent as less geeky and more heroic and sexy.
I am glad this change is being made and intellectuals will be seen as something to strive for in life instead of the image of nerd that seems to be a put-off to some people.