I think in the flight simulation community expectations are sometimes really high. The IXEG 737's most beautiful thing may not be something noticeable to someone who doesn't fly or hasn't flown a big commercial jet in real life, and that is it's dynamic behavior. It's a lovely plane to hand fly, I really enjoy disconnecting everything and just hand flying an ILS or a visual approach. Of course the FMC has some limitations (I will list HOLD and PROG pages as the two things I'll put on my 'need to have list', the rest falls under 'nice to have') but that's nothing compared to the handling the aircraft has. And in regards to VNAV... even in real life, in the newest Boeing designed, the VNAV many times gets it wrong and starts acting up.
Making a fully functioning and well simulated aircraft takes either a lot of resources (money) or a lot of time. However this is the aircraft I like the most of all the ones available for X-Plane. Keep up the good work.