Question: assuming that our primary interest is creating software for Wikipedia and similar WMF projects, do we actually get anything from the Windows PC intranet users that offsets the cost of keeping MediaWiki friendly to both environments? In other words, do we get contributions from them that help us do Wikipedia et al,?
As someone who originally started contributing from maintaining a small MediaWiki instance, I kind of dislike this question. I also don't think we should be mixing "we" when discussing WMF and MediaWiki.
But to answer your question: yes. We get contributions, we get employees, and we get a larger, more vibrant community. A number of contributors come from enterprises and small shops, but they often don't contribute directly to Wikimedia projects. However, their contributions often allow other people to use the software in environments they couldn't be used in otherwise (LDAP authentication is a perfect example of this). The people who then get to use the software may turn into contributors that do benefit WMF.
MediaWiki is created primarily for WMF use, but a lot of other people depend on it. I advocate the use of the software by everyone, and emphasize in talks that we want contributions from everyone, even if they don't benefit WMF. I don't think we should discourage this. We should really try harder to embrace enterprise users to get *more* non-WMF specific extensions and features.
It doesn't take that much effort to keep core small, and maintain extensions for WMF use. I honestly don't think this is a limiting factor to the usability of WMF projects, either.
Respectfully,
Ryan Lane