I think you're on the right track. For years, I have largely accepted the arguments for protecting anonymity in online discourse, but I am beginning to change my view on this, because I see so much rampant abuse. I think it might be reasonable for services like Twitter to require people to use their real-life identities, or at least make those identities known to the public.
I'm not so sure. It could also stifle legitimate political discourse, and anonymity is another safeguard against tyrants and oppressors, to borrow Jefferson's words. In the end, the identity of a twitterer is known: Twitter knows the IP address from which the tweet was made, and the ISP knows the real identity of the person. It's just one indirection. The solution lies, IMHO, more in that services like Twitter and Facebook assume more responsibility for what is published through them, and maybe expedited legal procedures for getting to the identity, than in flat-out requiring wholesale abolition of anonymity.
For my part, discuss your favourite case on whatever forum you like, within the bounds that forum (and the law) sets. If you have convincing evidence, bring it to the police and the prosecution; they're appointed by us all to prosecute criminals and get them convicted. But don't bully directly aimed at the people you think are guilty of crime.
ETA: Maybe this suicide is a wake-up call to other bullies. I fear not.