Hello,
All requests are treated in the exact same way, with no discrimination or exception. The Spanish project was created before the language subcommittee existed, so it was obviously not subjected to the same rules.
This is also why the Japanese wikis now exist without localization, but they would need to do it anyway! Were their wiki created now, they would have a partially English interface and need to translate it locally; then the next wiki would need to do it again. Translating the localization files saves work and time later, and allows Japanese editors to use a Japanese interface on any wiki.
Marco brings up one wiki that flourished without meeting these requirements (it predates them), but I can give a very large number of examples of projects that *didn't* flourish. Some interesting pages to see are < http://meta.wikimedia.org/wiki/Proposals_for_closing_projects
and < http://meta.wikimedia.org/wiki/Inactive_wikis >. So far as I
know, no new wiki since the subcommittee was formed has become inactive yet.