Basically, 'What about the Menz" happens because there's no actual space for people concerned about issues regarding men right now. Feminism has brought the topic of gender equality into the national dialog, and has also presented a place to discuss those issues for women, but there's no place to really go to discuss the otherside.

Feminists don't want to hear about it and obviously get upset about it, because the purpose of their movement is to give women a voice and a place to use it. They don't want men dominating the conversation. "MRA" sites/blogs/organizations tend to be echo chambers about how Feminism is ruining everything, or a weird culture reinforcing 'Manliness' and exacerbating the problem. Other activist groups dealing with gender tend to have narrow focuses and resist a change in the discussion for the same reason Feminists do.

So basically, there's a bunch of people that are being introduced to this idea of gender inequality, more the massive scope than the fundamental idea, and the people concerned about women have tons of places they can go to have rational discussions about it. The other people concerned about men don't really have any space to have reasonable discussions that don't involve just blaming Feminism for everything or being shouted down for bringing 'What about the Menz' into a conversation.

I figure they see Feminist organizations and think "Hey, they say Feminism is for everyone. They actually talk about this stuff and try to do stuff about it. I'm concerned about [Prostate cancer awareness/child support laws/archaic alimony mandates/the draft/unequal education standards/blah blah blah], so I'll bring this up there." Of course that doesn't work because no one there really cares that much about, they've got bigger fish to fry right now and don't want to split their attention. So those people concerned about X are basically just left with issues they think are a big deal, but no one to really discuss it with.

You bring up an issue like this and it has strong parallels with whatever they're concerned about, they're going to talk about what they see as their side of the issue, because there's nowhere else to bring it up. Its not fair to you, definitely, and its far from your responsibility to do anything about it. The people who actually care about men's issues, and don't just want something to blame Feminists for, need to actually create their own space for rational discussions, and then invite other people to talk with them about it instead of constantly crashing someone else's party. Its just going to take some time.