if your in an abandoned building and see broken windows, you're more likely to throw a rock and break more windows
if you don't continue to improve a system, then your devs are more and more likely to continue bad practices and even make things worse for a quick win
maintaining and monitoring urban environments to prevent small crimes such as vandalism, public drinking, and toll-jumping helps to create an atmosphere of order and lawfulness, thereby preventing more serious crimes from happening
I lurk on https://legacycoderocks.slack.com and read an awesome discussion on why constant system improvement is important
https://en.wikipedia.org/wiki/Broken_windows_theory