I actually talked this over with chx in the IRC, and said I'd send my thoughts on it to the list, and then didn't do that part. Mea culpa.
Here's my theory:
Scratch a). Can't call them release critical, because you can't have someone falling asleep at the wheel hold up things for everyone else. That said, b and c are important. But it's more than just b and c.
The Drupal developer community is not exactly a perfect society - it is anything but. I honestly do not believe that any of the points outlined will actually succeed unless these modules are deemed release-critical. It is a practical requirement. IMO, this will just not work otherwise (call me a cynic). Falling asleep at the wheel should/can be remedied quickly and effectively. There is no perfect solution, but if these modules have multiple maintainers (thanks Derek :) , such occurences can be minimised. I personally don't see this being much of an issue except for modules like Project where there's a dearth of volunteers. Consequently, modules like Project, i18n and so on will IMO benefit immensely from such a system. But generally, as the modules in question are popular, there should (hopefully) be no shortage of contributors.
So here's my version of the proposal. +1 for the rest.
Let's try and get this out (release-critical or not) with a trimmed list of modules first and have endless debates on the importance of any modules at a later date. Thanks, -K