I think it depends on the type of lack of confidence. Some people become shy, put others before themselves a lot, are loyal and really appreciative of their partner etc. They're attractive people to have as partners.
Others complain, are passive aggressive, never compliment or help others, don't appreciate their partner because they moan to themselves about how they want someone more attractive if only they had the confidence to get them etc. Theyre very unpleasant people to be around.
In general women want to be taken care of and to feel protected. People who lack confidence aren't great at taking care of people or making them feel protected.
Women also like to look after and nurture people, which is why people who lack confidence or self esteem in the first category above can be attractive.
Very nurturing and naive women may go with people in the second category, thinking they can help them, but instead end up feeling abused by them and like they've had the life drained out of them. They probably won't make the same mistake twice.
People in the first category can also be exhausting and annoying because they need constant help and nurturing, so probably only the most caring, empathetic and patient women would be able to stay with them. However, these women require lots of emotional feedback too, so if you're a non confident aspie of the cold, non empathetic variety, it probably still won't work out well.