I think everyone should release the source code of the game. It could have a link to the source in the main page of the game in java4k site. With the source code we can learn and improve our skills and build even better 4k games.
I agree with you, everyone should even release the source code of any program (not only 4k games) so that we could learn and improve our skills. However, lots of people still think that sharing should be only an option while I think sharing should be the rule.
We could do something like save the source code and only release it after the results but again seems too long winded to be worth the effort.
It is a good idea in my humble opinion.
Anyway, maybe sometime the source if so complex that we cannot learn from it...
Even a complicated source code should be instructive if it is well written and documented. I learned a lot of things by reading the source code of Art Attack in 2006...