JSPWiki is one of those things that once it's installed, people use it
and don't look back.
For example my personal wiki is version 2.0.56 (with custom security
patches developed back then) and it's done everything I want.
I've installed versions since then at a number of customer sites. All
of the CSS work to make it look like they wanted was done as contract /
work for hire, and didn't come back to the base release (which is within
the license terms). Most don't use custom plug ins, the base set gives
them the collab tools that they want and need.
There are other wiki's out there that get good use. About eight weeks
ago I installed MediaWiki at a site, the lead admin is a PHP guru, he
wanted something he could understand. Since then, they've updated the
css to make it what they want look and feel, but they have not written a
single line of PHP to change the code base.
Most places take the base tool, add the dancing sauages they want on the
graphics and are good to go. The largest site as 12,000 pages on a 2.6
release and they are happy as clams.
I'll grant that the hardest part is the documentation for users.
Foster