I do see your point & I must admit I didn't 
consider the legal implications about posing as 
someone else.  BUT (and there is always a but:) a 
lot of damage can be done that way, especially if 
someone does it so prominently.  Reputations can 
be damaged before any restraining actions can take 
place.  

I know this is a lot of work, but what about 
anyone could read the forum, but you have to 
log-in to post?  I guess then that again restrains 
free-speech, etc.

Or if people find it troubling to remember to 
write their name or email at top (I think someone 
already mentioned this?) they could get that gator 
program that auto-fills certain fields.