It's not really closed, it's more like an "open beta" that requires registration first. I signed up just out of curiosity and submitted a bug report (which was a known issue, d'oh) and it never felt "closed".

You can sign up here https://launchpad.net/~ubuntu-typeface-interest after which you will be given access to the "private" https://launchpad.net/~ubuntu-font-beta-testing where you can download the beta.

edit: oh, it says all that at the top of TFA.

One possible reason is that people tend not to upgrade their fonts. Therefore, old and buggy versions would remain out there, and lots of people copy fonts from their friends instead of getting them from the source.

It's a difficult problem: what's better for free software? Sticking to our principles of open development even for assets, or ensuring that potential new users see a high-quality, finished product? I don't know the answer.

They're distributing it through a PPA, so assuming that you click "Install" when update manager bugs you once a week, you should have the newest version.

It's a good question, during the previous font testing Canonical has given us access to the "font bug tracker" but the link (http://fonttest.design.canonical.com) seems to be dead at the moment. Probably oversight on their part?

With all of the Ubuntu fonts so far they've released to a limited beta group and then moved to public testing (with bug tracker). I'm not sure I agree with keeping things closed for so long, but I suspect it makes the design side much more pleasant.