Absolutely, and the work versions are very useful for that purpose. My concern is that diffs between work versions tend to be rather large (for instance, my 5.2 to work2 has several thousand lines touched. If there was a more granular patch series, then each language change could be digested separately over time.
A publicly available repository does not need to imply public commit access of any kind, nor would it mandate that developers use that repository in their daily work. In other words, it wouldn't suddenly make Lua a democracy. ;) It would at minimum provide a more structured way to provide updates to the public.
I don't want to make a big stink about it, as I understand the hesitation to a more formal method. I just think it should be on the radar, just as other organizational controls like strict API stability are on the radar now that Lua has sufficiently matured.
