I'll take a stab at it.

1) Because society is predictable. Groups act in predictable ways. Everything that's predictable makes sense.

2) But good friends do.

3) A well socialized nerd can interact with different groups. He is comfortable with hostile nerd speak (where you must be able to back up every statement with layers of facts) and he's comfortable with small talk / casual conversations with "normal" people. Most socially well adjusted people on the other hand can _only_ talk in their setting. They're completely lost as soon as they're in an environment with different social rules. (Of course there are obvious exceptions)

4) I agree. But the difference between people who are socially really smooth and "most people" is probably just as big as the gap between "most people" and socially maladjusted outcasts. If I pay a little attention I see regular people make big social mistakes all the time.

Good points, but #3 isn't universal. Rather a few better-socialized nerds get annoyed at anti-social nerd behaviors.

4) all people have emotions, not so many have picked up the abstractions needed to do good math,

and some even have bad emotional controls so that they can't see a rational process through for more then 10 minutes.

this is relevant because social skills are largely dependent on emotions (love, trust, fun, ...)