I see a few problems with having real names that are inherent to the system, but a lot of the problems exist because of things that weren't a factor back in the Usenet days. The internet is more popular, meaning a lot more people are aware of it. It's semi-permanent, meaning there's a good chance something you say now will still be visible ten years from now. Plus, it's searchable: if someone's looking for you specifically, they'll be able to find what you said if you associated your name with it. What this means is that if people are looking for dirt on you, if your name is tied to everything you say, they're likely to find it. Maybe you said something controversial, maybe you just associated with something that seems "weird." It doesn't matter, the problem is that if your name is attached, someone might use it against you in some way, and that leads to people being overly cautious and opting to remain silent on things that they shouldn't need to remain silent about. That's the biggest problem I see: people shouldn't be scared just to talk about something. There are other things at play, but that's the most important, I think. There's nothing inherently wrong with just discussing things and it shouldn't be something that can come back to bite you in the ass. I don't think that was a major issue back in the days of Usenet, but I don't think I could spell "internet" then, so I might be wrong.
I agree that letting overtly malicious people say whatever they want is a bad thing. I'm not advocating chaos, just the freedom to talk about things without fear of consequences, whether it be intelligent discussion or just for fun. You're right, there is no "right" answer, but I do think that real name association is definitely a "wrong" answer. At this point, it just causes too much harm.