Because most girls tend to fall for guys who are bad and will just treat them like crap. Remember what he did to Karin at the end of the Danzo fight?
The only aspect of Sasuke I like is his hair.
A bit of Kakashi-intelligence, aloof (if I don't know you) and I do like my books lol...
And a bit of Kushina-I have her temperament and am most like her looks wise.