I vote "nay". If I'd had to become a member to post the first time, I probably wouldn't have done so. Now that I am a member, I don't have a problem with being one. I say that allowing guests in is a good thing. It does raise some problems, but all in all, the problems here are nothing I haven't seen in other forums.
Besides, and I may be being naive here, I'm not sure that even registering people as members will stop the flames and trolls, etc. I mean, what are you going to do with them if you register and catch them? There's no legal recourse. And if there was, the expense of pursuing it would be prohibitive. You could ban them from the forum, but all they'd have to do is re-register using a different name and false email account.
I say that patience, a realistic view of the cyber-world, and adult behaviour will win the day before any attempts at legislation.
I'm just sayin' is all.