Academic code should be released. In fact, I believe that you should host everything on a public github/bitbucket from day 1.
I don't like the proposal in this blog post, i.e. that we insist that code must work in a distributed fashion under some consortium guidelines. Increasing the friction to releasing code is the wrong approach.
I believe that open notebook science should be incentivized by being aligned with career goals. Publications and conferences should have separate tracks where you cannot submit unless you will release your code. Then, academics who want to release their code have the edge, because these tracks are lower competition.
The feeling that you must release polished code is the wrong idea. Pushing everything to github removes the friction in sharing code, and has been successful in the past.
The author complains that neither he nor his students have the time to polish code or write documentation. Here's my solution: I've released research code under a "pay it forward" support license. If you ask me for support, and I give you support over email, please document what you learned through your investigation and discussion with me, and then push your changes to me.
[edit: formatting]