The only reason most (not all) VB forums require registration like that is there is no other way with the current release of software to prevent flame wars.

Here's another idea from a low class, scum of the earth, Unregistered user:

If you made the "report this post" link go to a counter that counts per different IP address, then if enough people hit that link it would automatically move that post to another area or close it or hold it for review. How hard would that be to code? It's already a separate php page.
That way the mods will only have to deal with posts that are truly annoying.
You should change the link's line to something like
"click here if this post is inappropriate"
"this post sucks"
"click here if this is a flame"

Give the power to the people here.