Besides the reasons mentioned by others, I want to add: discipline. Keeping codebase well maintained requires some effort and often it's very tempting to cut a

Besides the reasons mentioned by others, I want to add: discipline. Keeping codebase well maintained requires some effort and often it's very tempting to cut a corner here or there, or to focus on adding new features instead of keeping dependencies up to date. Initially these shortcuts don't have a big impact, but at some point you notice it all became messy, and now it's hard to bring it back to shape.