Having more than one emulator available is good for people trying to get into development. It is still common to guide newer developers toward writing their own emulator for a very well understood system to gain an understanding of some of the more high-level concepts and abstraction. Having multiple different codebases gives you ideas on how to implement features in new ways.

Of course, the cynic in me says it doesn’t matter if the products aren’t competing in feature sets, the more robust system will be used and developed, but I don’t think that’s the point of the exercise.