I mentioned this when it was brought up before -- the implementation would have to be key. With a catalog of (just checked, wow) 2400 bumps and a couple dozen (?) site regulars, if it were ever done, I'd recommend a way to track when comments are left. Like a "recently commented" section on the main page like the "recent updates." Otherwise, every 20th bump or so might have a comment and noone would know unless you just happened upon it.
An alternative may be a forum subsection specifically for bump comments. Or maybe someone choose a bump every few weeks to discuss and make a new thread about it. The old English class critical appraisal. Anyway, just ideas.