We are sharing the same concern - some of your suggestions are happening under the hood. I can add another speculation to your list: most language pack maintainers do the work voluntary in their free time. What people spent their spare time on, can change.
First contact of new translators usually goes via email with me. In our email contact we sort out some of the problems mentioned in your post, at least problems which can be sorted out. A very often asked question is indeed which files contain the strings for the students. As you know, that can't be answered. I created a translation FAQ that addresses some of the issues on http://docs.moodle.org/23/en/Translation_FAQ
There are not that many new translations started anymore - what happens the most is people taking on an abandoned language pack, which is good of course. Occasionally someone has a locally maintained language pack to share. It's a shame people maintain a local language pack, because it is a lot easier to maintain it on http://lang.moodle.org and then it is shared in one go. Being someone who likes to share work, I don't understand peoples objections against that.
But people speaking a (minority) language have their own responsibilities: if they feel the need for a language pack, if they feel the need to cooperate and share, the platform and the people to help them are here on moodle.org. Open Source software is the only way to go for having software translated in a minority language and personally I find this really important. Those 60% of poorly maintained language packs can be a starting point or a motivation for those people to get on with it.
I'm giving your idea of contacting the admins a thought, but again, it is the responsibility and the choice of the people to share their work.