I have a negative impression about anyone who is dumb enough to call themselves an MRA. I think this is a result of identity politics, where every additional label you tack onto yourself limits ties you down to another set of stereotypes.
Even if MRAs don't intend for it, people are naturally going to compare men's rights activism and feminism. And that's not a favorable comparison for MRAs. When MRAs make that comparison (even unintentionally) they come off as excessively dramatic. And there are plenty of MRAs who make that comparison intentionally, and those people are huge dumbasses.
I think
@Alberto Balsalm hit the nail on the head. The term "feminism" has lots of historical currency. I think that men's rights activism lacks that historical currency, and that most people willing to label themselves an MRA are dumbasses.
Of course, lots of internet feminists are doing their darndest to piss away that historical currency. But as long as women's suffrage is still a part of our cultural memory, I think feminism is still pretty solid. Heh, also, Islam is helping remind people that feminism is still important. Thanks Islam!
All that being said, as people have touched on, there are some huge issues that exclusively affect men that need to be addressed. Men get discriminated against in divorce proceedings, they're constantly under suspicious of pedophilia, and yet male victims of pedophilia (especially if the perpetrator is female) get treated pretty shittily, they're subject to impossible standards of masculinity, etc.