When things 'heat up' and the undesirable posts start to appear we do have the ability to curtail posting by Unregistered Users (and we have implemented this in the past), but your thought certainly has merit. Most unregistered users just visit the site to read, but if you wanted to post, I guess that its true that if you had to register before you could post, you might tend to be a little more diplomatic about what you said in your post. It doesn't always work out that way, but the Mods usually do a good job of keeping everybody on an even keel.

Some folks will get nervous when a storm approaches - and thats normal, however, posts that are driven by panic, hype and/or a personal vendetta are the ones that are troublesome since they can confuse other site visitors, and registration prior to posting might eliminate at least some of those. Certainly an idea thats worth further consideration.
Thanks,
ED