So, something like a specification for MediaWiki
wikitext should be
agreed upon (in a text document, not in the MediaWiki PHP code). After
that, on a solid foundation, nice gadgets can be built to help people
built tables and templates.
People have been working on that, but doing so in a way that preserves
backwards compatibility proves challenging since the existing code is
very idiosyncratic. Ideally, we need to make a new syntax from
scratch, but that clearly isn't an option.