Yep. Increasingly, in fact.
While I don't hold the big wigs and idols accountable for the actions of their fans (unless they are directly or indirectly but obviously encouraging the bad behavior for the sake of monetary gain or whatever), I do think it should be a common practice for them to check some of their behavior. Huge negative hashtag trending against a group? Check that. Photoshopped images spread depicting murder or making fun of someone's relative, alive or deceased? Check that. Hate campaigns launched on the false accusation of sajaegi (whether it's an idol, idol group, or solo artist not as well known by i-fans)? Check that.
It's harder to check regular internet trolls, regardless of what kind of fandom (sports, comic, k-pop, what have you) you're in. Trolls are trolls. I think, though, that there are certain behaviors that transcend being a troll, and that is something that should not be encouraged...or ignored. True, folks are gonna do what folks are gonna do regardless, but at the very least the companies/idols/groups/whatever don't have to be all "I just work here" about it.
Small change is better than no change, methinks.