Why?
Well, you've got the VTOL bit nailed so simply flying around and landing on things you ought not to will be great fun. And compared to the AV-8B the avionics are much simpler; no MFDs, FLIRs, Lasers or any of that stuff. Also when the new Kuznetsov model arrives it would be a perfect marriage.
Yes it was a bit crappy in performance and payload but so what - it's such an interesting subject.
Sometimes a bit too interesting....