Organizational culture matters here. There is little benefit to fixing things if you have a culture where speed matters above everything else and people are rewarded on how quickly they can do things.
I still remember the time I spent weeks working with a giant mess of undocumented (or, worse, documented incorrectly) code to get my job done as the first engineer at a startup. We had a new hire coming (and lots more coming after that), so I took the time to clean everything up and document all the fixes, then trained the person instead of leaving them to figure it all out. Result: they got up and running within a few days instead of a couple of weeks.
Of course, when review time came, I was told that the new hire had gotten up to speed much faster than I did, which was why they were being promoted over me...