I've spent two jobs rewriting software. The two main reasons for it: 1) the original was a prototype; 2) the requirements have changed so much that the original

I've spent two jobs rewriting software. The two main reasons for it: 1) the original was a prototype; 2) the requirements have changed so much that the original architecture doesn't make sense. If it's either of these situations, then a rewrite can make sense. Contrast that with developers wanting to rewrite because of vague frustrations or poorly-defined technical debt. Without a strict definition of the problem, a rewrite is doomed to repeat the same shortcoming as the original. I've seen the most success happen on teams which can figure out how to rewrite the app one module at a time, while keeping the existing parts functional. This reduces the risk, and allows you to compare the new effort against old code more directly.