Why do I have to be confident (Boys)?

It isn't important to anyone but yourself that you are confident. Although, confidence and intelligence is attractive.

I don't think it has so much to do with women being confident as I does them not coming off as unconfident and awkward. So I don't think guys like women who are confident so much as being unconfident pushes them away.

Err...both posters, in the latter part of their posts, essentially said it was important to be confident.

Confidence makes you charming, even though you are not beautiful as a girl

It's simple, men are attracted to powerful and confident women, same as you girls are attracted to men.

Generally speaking, men are NOT attracted to women more powerful than them (there's always exceptions to such 'rules')

And few relationships last where the male doesn't feel needed in some way (ie. the woman displays some vulnerabilities, and is in need of some help in some part of her life)

That comes back down to genetics, which appears to have made general rules, but not hard and fast rules.