That's because they are actually REGISTERED users who want to flame someone but not take the blame for it.
If they have a normal post, then they log in, but only use Unregistered to flame.
So much for registering saving you all from flames.
Now go and match up the IPs of all the flames against the IPs of registered users and let me know what you come up with, and don't forget to ban those registered users who flamed.
If they didn't register then they wouldn't have to worry about some mod with a bad temper removing their account because they posted against that mods favorite client.

I think people fear the unknown.
I think people fear things that are different.
I think people have a herd mentality.
Seems kinda insecure to me.