Just a few weeks ago, I had to dig back to try and root cause a very old bug. It ended up being in code from back in early 2012, but the root problem was drift in functionality that it didn't keep up with and eventually broke in an unexpected way. I would never have known the context around why that code existed in the form that it did without being able to go back through the history.
Granted, the context didn't really change what the fix needed to be, but it did provide a useful moment of reflection on the ways in which software can break through subtle changes over time that stack up, and it helped to know that the section of code that broke was indeed originally intended to work the way it did (and not that it was a bug from the very beginning).
Granted, the context didn't really change what the fix needed to be, but it did provide a useful moment of reflection on the ways in which software can break through subtle changes over time that stack up, and it helped to know that the section of code that broke was indeed originally intended to work the way it did (and not that it was a bug from the very beginning).