Not understanding
"What I don't understand is why they didn't just make Java/JavaFX a center piece of this approach. I find it so ridiculous that companies always go about reinventing the wheel over and over."
I guess you simply do not understand the difference between Java and Native Code. The first is inherently (because of the memory model of the JVM) inefficient in terms of runtime and memory consumption. Realtime responsiveness can't be assured by Java (except if you use it in a strange way (no new statements after startup)) .
I guess you know what can be done by C/C++ based games, photo/video editing applications, CAD systems or relational databases. Native Languages like C/C++, Pascal, Fortran or Ada allow good programmers to write efficient, small and realtime-capable programs.
Google knows the difference between Native and Java(or .Net) while the drones of SUN (McNealy et al) were only able to generate excellent media spin.
Of course, you could heavily tweak the JVM specification to make more efficient programming styles available (e.g. allow for objects on the stack, allow for reference counted pointers, allow for destructors), but the result of that would be as much "Java" as "JavaScript" is "Java". Certainly it would make everything much, much more complex and that is why the controllers of the JVM spec at SUN always refused such ideas.
You know, SUN is the "Stanford University Network". Don't expect academics to create something that is useful in the real world. What they do is a proof-of-concept and Java is no exception.