All of these features are availible in Mathematica, so it is incorrect to say there is "no analogue" (in the sense that Matlab has no analogue for symbolic solutions of ODEs).
The Mathlink protocol can be used to establish two way communication between C++ apps and the mathematica kernel. In fact, I can pass models from Simulink into mathematica (I don't care for the diagram interface).
Mathematica has always had the ability to create real-time GUIs, but untill now it always required java (just as GUIDE requires C++) and manual coding (unlike GUIDE) . The GUI creation system in mathematica 6 looks to be the most streamlined I have seen anywhere, but we will see.
Your right, I was too stupid to realize that there is room for both products. I have been blinded by naively pure academic inclinations, without concern for brutal practicalities. Matlab is much cheaper, and much better suited to the field of engineering for ever reason: the engineers, the type of work they do, and the way they do it. It will take many more upgrades to Mathematica before it will begin encroach on this domain of application.