Girls are not accustomed to jockeying for status in an obvious way; they are more concerned that they be liked.
Part of the reason (motherly advice) bugs us as daughters is because our mothers are so powerful in our lives. They loom like giants. The reason mothers keep at it is because they're so powerless. They cannot get you to do what is so obvious to them you should do.
It was just so obvious that everyone wanted to talk about the mother-daughter relationship. I think it's because women really are struggling, because it's a very important relationship in your life.