We've talked before about how ProjectForum and CourseForum are examples of what we call "workgroup" wiki software. So unlike something like Wikipedia where you have the whole world involved, it's more geared for smaller groups collaborating. Usually it's several different - but sometimes overlapping - groups using the same ProjectForum server, in separate workspaces or forums. By focusing on that usage pattern, the feature set and design can be optimized to fit those kind of work patterns.
The other aspect of workgroups is that most don't have the budget and/or IT resources (or time!) to deal with installing or learning expensive, complex software. So we've made ProjectForum affordable and very easy to install without any complex infrastructure or IT expertise needed.
If you've been following some of the other wiki vendors, you'll notice an increasing emphasis on so-called "enterprise" features. For software companies, "enterprise" is where the big money is; large licenses sold to bigger companies by highly paid salespeople for 5-6 digit fees (plus support and installation and training and consulting contracts to match).
And do you think if you're charging that much money the product can be up and running smoothly in a minute or two? Not a chance. Complex infrastructure needs, elaborate administration setup, and a multitude of integration points help "justify" the fees.
Not in that class? Ask yourself if the enterprise products are really what you need.
(We have an enterprise license for ProjectForum, but it's not that much different than the regular license, and just as easy to install and use. The main difference is a more fine-grained access control model that more closely matches usage patterns for some larger organizations than our regular license).