This is a rather random question, but... I was thinking about all the "forum" sites (such as this site itself), and how sooooo many of them run "commercial" (non-free) software, when there are free (OpenSource) programs available.
Obviously, I'm not expecting everyone to immediately delete vBulletin &co, but I'm curious as to why for-pay software is so popular -- does vBulletin offer features that things such as phpBB2 don't, or is it just a "Why bother switching?" type scenario? Just wondering.
