Hi Enrique,
please don´t take this as an excuse that our VNAV is not working very well - it should be and we have full intent on fixing it. But I flew the 737 for 10 years, another 6 years of 747-400 and too many years A320... it is a very rare circumstance that I have descended (or seen my FO/CPT use it) using VNAV. Most of the time your routing is not predetermined (vectors, shortcuts) or you are subject to ATC limitations (early/late descent, advised rates of descent). So for me (and many of my fellow pilots) VNAV is a gadget that serves very little practical purpose.
I think VNAV is so important to many flight-simulator pilots because they lack the ability to make accurate descent calculations in their head and they also think that it is "cool" to watch the plane glide down all by itself (and then autoland!). I think that is about as cool as using a Tesla´s autopilot when playing a car racing game .
Oh and yes - we do eventually plan on making a cargo variant for the 737 (I see the pattern!)
Cheers, Jan