I'm not sure this is specific to the tech industry. Right or wrong, I think that "be competent at [job] and pretty/sexy/funny/personable" pressure is something a lot of women feel in a lot of jobs. I think a lot of times, that pressure is more imagined, or self-inflicted, than real.

As a not particularly attractive, introvert, female developer who has been rather successful in my career, I don't feel like I've missed out on any opportunities because of those traits.... and if I have, they're probably people I wouldn't want to work with, anyway.