I know no one has posted on this thread in a while, but I find this topic interesting and I just wanted to add my 2 cents.
I remember wanting a bra as a very young child (maybe seven), but being too embarrassed to say anything. It was about wanting to feel grownup, and had nothing to do with wanting to be sexually attractive. I just wanted to be like mommy. I think one thing adults forget is that children see things very differently from them. Now, I don't think little kids should be wearing thongs or pushup bras, but if companies sell toy phones and other "grownup" things, how are bras any different? They are, but a child doesn't see it that way.