(Note that I think any conversation about parser changes should consider the GoodPractices page from http://www.wikicreole.org/wiki/GoodPractices.)
If nothing else, perhaps there would be some use for the EBNF grammar that was developed for WikiCreole. http://dirkriehle.com/2008/01/09/an-ebnf-grammar-for-wiki-creole-10/
WikiCreole used to not be parsable by a grammar, either. And it has inconsistencies like "italic is // unless it appears in a url". Good to see they improved.
WikiCreole only had a prose specification, hence it was ambiguous. Our syntax definition improved that so that in theory (and practice) you could now have multiple competing parser implementations. The issue with WikiCreole now is that it is simply too small---lots of stuff that it can't do but that any wiki engine will want.
The real reason why to care about a precise specification (that is not, as in the case of Mediawiki, simply the implementation), is the option to evolve faster. The real paper for this is http://dirkriehle.com/2008/07/19/a-grammar-for-standardized-wiki-markup/ - wouldn't it be nice if we could be innovating on a wiki platform?
Cheers, Dirk