You freaking kidding? What about the rampant homophobia and racism that is incredibly more prevalent than trolling women (half the time it's just horny teenagers coming onto them, not an attack on their "minority" status) ??
While I think you underplay the actual harassment towards women online, you definitely have a point. Anyone who isn't a straight white male teenager will face discrimination and harassment over who they are when playing online games, but it's because of outside factors that these people are morons.
In terms of what video game companies should do, it would be hard to monitor every single person and what s/he says as well as an invasion of privacy, but there should be something done. I wish I knew what it was.