Copyright assignments are harmful. They are not some
sort of standard
thing in open source. They would be harmful to MediaWiki.
At the risk of de-railing the discussion, I think everyone can agree
that having good high quality extensions for MediaWiki is good for
MediaWiki. The license an extension uses does not harm MediaWiki in
any way. Nor is this discussion really aimed at proposing a
re-licensing of the core. Please stay on-topic.
The question is should a WMF-funded service (and the MediaWiki
community) allow 3rd party to make use of said services if they have
dual-licensed code.
They are already contributing positively to MediaWiki a) they have an
extension we can use that better our lives (maybe) and b) they are
releasing at least a portion of their code with a permissive license
which everyone can benefit from. Whether it be GPL or otherwise. True
maybe we could benefit MORE, but it's not harming the core or the
community.
- Olivier