I consider american PC towards women (or blacks etc) as a symptom. What makes you think it helps, other than overstating the problem (which in itself does not solve it)?
There are several definitions of sexual based discrimination, one is essentially "making references to someone's sexuality and implying everyone in that group is the same (in some attribute)". Lots of people like this definition because it's nice and simple and it means homosexuals can be discriminatory or joke about straight people.
There's another definition, which is talk that's designed to maintain & reinforce the institutionalised power structure among sexualities (specifically to maintain advantages that heterosexuals have). Right now, if modern USA/Western life was a video game, "straight" would be an easier difficulty level than "gay". There are statistically less problems for the "straight" group. Sexual discrimination talk is talk that re-enforced that imbalance. This definition is harder for some people to accept because it means that you need to look at yourself and think about what power imbalances you might be benefiting from, and it means you can't just do s/gay/straight/g and make it just as racist.
How is that, by itself, not helping?
[1] Interesting, to me, because I think of it as starting in the late 1980s: http://en.wikipedia.org/wiki/Political_correctness [2] Credit to Vonnegut