Why is there suddenly a trend where girls like "nerdy" guys?
It's just what is popular at the moment. The nerdy/indie/alternative image is 'in' so people flock to it and change their wardrobes, music taste, hobbies and men to suit. Of course the genuinely nerdy guys aren't included in this and are resigned to some other label for now. It's just the new ones with the nerdy glasses, cardigans and skinny jeans that qualify nowadays! 