In the intended workflow, the PR itself is a very small part of the process. You fork the repo, study it, analyze it, work on it, test it, ..etc (99% of time spent), you create pull request (1%). Plus there is a reason for the PR - you describe your changes, provide reasoning for them, allow many parties to review them.

With the concert request there is nothing to do, just create the request with specific data (something that would work MUCH better through a web form) and there is no reason to have it public as only relevant people to comment are you and the band's manager (something that would work well through email).

Maybe for this particular use case, I don't really see how it says anything about the UX for actually using GitHub for it's intended purpose.