Indeed MoI's primary functions is communicating ideas, and support for real-time shaders could be really cool.
But as designers our prime goal is to turn these Ideas to reality.
What I am trying to say in a inarticulate way, is that MoI is a great but not complete (yet) modeling tool.
In my case MoI has helped me to produce five products the last ten months, and for example I fund it annoying when I have to use other apps for simple dimensioning, technical documentation etc.

And yes real-time shaders support could be a plus but it should come after is a Modeling Beast IMO.