I'm sure a lot of professional musicians would probably prefer to use something less fragile than a laptop, something you can rack up, with no pesky desktop OS niggles to worry about during a show. As you know many instruments today are simply dedicated VST runners with a handy physical interface, see Roland's Boutique and Aira synths. I have an MPC One which I love, it can run proprietary VSTs. Maybe such convergences have killed the need for a dedicated box.
I know for a fact new devices like this are on the horizon, but it just might not be the form factor that you are looking for.
It's actually a golden age for the MIDI fan but there's a lot of complaining to be done too about aspects of it. Cheapness and hooking you to a store being two big ones.