The reason they have their own topic is so people can block the topic if not interested.
They are quite different. Rate me in some form or other has always been a part of the site since quite a few people want to know how they look.
He post a pic questions to me actually help build the community. One of the things that keeps me active here is the community aspect - if everyone was anonymous all the time I'd never have kept coming back.
Girls need to give themselves higher self-esteem. They shouldn't need to post a "How Do I look" post. They should be confident already that they have a great body. Any guy that trashed them - they need not to listen to a guy like that. But they shouldn't listen to someone who is always rosy, either. Find someone that can give CONSTRUCTIVE CRITICISM.
Everybody needs a bit of honest criticism now and again about their looks, since so many people in person are damned afraid of offending someone.
As for the "post pics of yourself doing XYZ", those are to give a more intimate feel to this website. The community feel (vs a passive forum site), is what makes GirlsAskGuys unique compared to other Q&A websites.
I typically don't open the rate me ones anymore. There's always 1 or 2 people being unnecessarily rude on them and I tend to try coming to people's defense and it just never ends well. So I don't really answer them anymore.
I don't mind the "post your pic" ones tho. I've posted a few myself and I almost always answer them. I think it's fun and it makes the site a bit more personalized and a bit less robotic. I find it weird that people (not aimed at you) will openly take advice from a virtual stranger, but will pitch a fit because people post pics.
I'm not bothered by it. If I don't want to answer any of them, I just simply don't click on the questions. As for the post your picture questions... I've done some of those for fun... I see no harm in it.