There are still version control systems around that don't have the concept of a commit of multiple files, Rational ClearCase for example. So if your change involves multiple files, undoing it requires remembering which files where involved and undoing each one separately. That's quite a pain, especially if you delete whole files that you want to have back.
Yep, especially since ClearCase records adding/removing files not only as a change to these files themselves, but also as a completely separate change to the parent directory. Really terrible system.
