Why do we need this? PCSX2 works great and is very mature
Emulation - Retro Gaming In Style
A community for discussing emulation and preservation of retro games. This community is intended for discussing the art of emulation, the tooling involved and retro gaming in general; it is not intended as a dump of ROM files.
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.
If the point of it is indeed a learning project then it makes sense to me.
A side note: The free market and competition making products better are both good arguments too but my counter to that would just be that PCSX2 is just so good and mature.