The advantage is time. Many (most?) embedded environments are overly difficult (IMHO), and/or proprietary. Also, even in a good environment, C/C++ typically requires more lines of code than dynamic languages like Python or JS.
Therefore, the industry has been looking for ways to combat both the below par developer experience, and the development time. Samsung's Jerryscript [1] is another example.
That said, I think these things are aspiration more than they are practical.
Note: Edited to clarify C++ vs. dynamic languages.