But if our core purpose is to get information to people, isn't simply any language they can read well the proper criterion?
From http://wikimediafoundation.org/wiki/Home: "Imagine a world in which
every single person is given free access to the sum of all human knowledge. That's what we're doing."
If the core purpose is primarily to provide information to people who can read then this should be accordingly changed on the website. And, there is a huge amount of human knowledge hidden away in many nearly-only-oral languages.
(And what is a "mother tongue" anyway? There are definitely people who claim some European regional language as their only "mother tongue", and say they only read/write/speak the "mainstream" language out of necessity.)
That's true, but I think they are wrong :) Though giving examples would probably lead to a big flame war :)