In several of your posts, you seem to be talking as if it's ---Meet someone---Instantly decide to start a relationship with them or reject all interaction with them forever.
If you are not physically attracted to someone, and they are looking for a relationship with someone who is, I would say it's misleading and unfair to start up a relationship with them. I completely agree that getting to know someone's personality is often the thing that triggers being physically attracted to them, moreso that the first impression of their appearance. I also think it's great that you were supportive of the girl you mentioned through her confidence issues, and obviously it worked out well as you became physically attracted to her. Unfortunately, there's no way to predict whether that will happen. Imagine if you'd started a relationship and then had to end it telling her 'Sorry, I just never found you physically attractive' - she'd probably feel devastated and very much misled.
I don't believe it's right to start a relationship with someone on the off chance that you may find them physically attractive in the future. For me, it's much better to remain friends and get to know them better, be there for them, and if the attraction develops THAT is the appropriate time to start a relationship.Of course there are always unusual situations. For example, if you were on a dating website and met someone, or set up on a blind date, if you get along reasonably well it's fair enough to go on another date or two to give yourself time to figure out if a physical attraction is going to develop. But if we're talking about the much more common situation of knowing someone first as a friend (as the OP is) then it doesn't make sense to me to start the relationship before an attraction develops. My husband and I were friends for years before we became attracted to each other, to start a relationship before then just because we were nice people would have been ludicrous (and also confusing... surely by that logic you'd want to be in a relationship with all your friends?!).
EDIT: Don't get me wrong, I'm not trying to say you were bad for dating that girl. You clearly liked her a lot and had her best interests at heart, and it worked out well. It just could have not! Also, I'm sorry about the mass of text, the site keeps deleting my line breaks
I used bold to try and make it a little better.