You can't really generalise about the readers of those magazines. I'm a generally academic person; I read all the time, I'm interested in politics, and so on. Yet sometimes I just want to relax and chill, and for babble, women's magazines are excellent. I don't think there's anything wrong with them. I'm certainly not obsessed with the way I look, for example; I skip through the make-up and fashion most of the time because it's just not me. I'm a very boyish girl. I'm in a long-term relationship, but if I wasn't, I wouldn't care..and that's partly because of the magazines emphasising the fact that it's okay to be single. There are articles about issues I wouldn't otherwise think about (identity theft, for example) and although I'm too young for it at the moment, a lot of career advice. Oh, and I learnt more about safe sex and respecting my wishes in that area from teen mags like Bliss than I did from anywhere else.
Yes, there is some rubbish, but that doesn't mean everyone soaks it all up. I read FHM for a laugh a fair bit, but that doesn't mean I'm gaining a stereotypical male viewpoint of sex, cars, and girls. You just can't generalise.