Since I have to deal with bad URLs on a daily basis, and just hit another one yesterday in a different repo, sorry, my opinion on this isn't up for changing. I actually thought (a long time ago) as you do now, but my experience with URLs is not that happy. Sorry. I expect that URLs will continue to make it into the repo one way or another, but I will continue to oppose such practice.
Committ messages are archival. At some point, when the Web was new, people would put URLs in citations (me included). That practice has started to come under fire in the archival literature due to the stale link problem. What we did when the Web was new is not necessarily what we do today. Few people in the 1990s anticipated the scale of the web as it is today. It's far more useful to put a searchable string (rocket systems 1984 superio with platinum thrusters) than a URL which will almost certainly be bad in a few years.
But if you're going to dump a URL in a commit message, for goodness sake, at least have it point at something other than a form!
ron