If the ports tor wants to use are already in use, try different ports before freaking out.
A user story: Imagine that you want to run two instances of Torbrowser at the same time. Perhaps you want to use one site in one instance and another site with the other, but who knows? You download the Torbrowser tarball and extract it twice — into two different directories. Now you launch one of the Torbrowsers. So far so good. You go to launch the other one, and… oh no, “Tor unexpectedly exited.”. Now you're sad.
Tor didn't launch properly because the ports it wants to use are already in use by the other Torbrowser's tor. You could fiddle with the config files to manually fix this. But it'd be nicer if Tor Launcher figured this out on its own. If tor didn't start properly, was it because the ports it wanted were already in use? If we just increment them all by one and try again, does it work? If so, let's just do that.