In a healthy and progressive culture, it can be tempting to rewrite poor-quality software from scratch, perhaps in the latest trendy framework, but this is usually a mistake. Released software is battle-hardened (no matter how badly it was built), and if you rewrite it, then you will probably make the same mistakes again, for example, reimplementing bugs that you have already patched. This is especially true if the software was not built with good unit test coverage, which can help prevent regressions.
The only case where you could reasonably rewrite an application from the ground up is if you had deliberately made a prototype to explore the problem space with the sole intention of throwing it away. However, you should ...
