It's a little bit naive to ask that question, isn't it? The decision to refactor internals is always related to how much technical debt the developers feel the

It's a little bit naive to ask that question, isn't it? The decision to refactor internals is always related to how much technical debt the developers feel the project has incurred, and how much easier they think it will be to develop in the new codebase. So every rewrite is a subjective call, where future ease of development and attracting/on-boarding new developers is traded off against short-term lost productivity and potential for bugs, incomplete rewrites, and dropped support.