Nice. JavaScript allocates a lot of memory dynamically, and sometimes implicitly, though. In very tiny RAM environments, that's going to be a problem.
It's extremely unpleasant to program something with just a few KB of RAM and not know exactly what memory goes where. However, a lot of IoT-related gadgets just gather a buffer of data from an ADC or something, average it and send it over some wireless protocol every 1 minute. The allocation pattern is predictable enough that you don't run into strange cornercases.
I see no reason why anyone would want to use this commercially, but for the enthusiast market (and maybe even for some rapid prototyping) this looks interesting enough.
Ardunino Uno (ATmega CPU): 2KB RAM, 32KB ROM - Too small.
Arduino DUE (ARM CPU): 96KB RAM, 512KB ROM - Yes.
Raspberry Pi (ARM CPU): 256MB RAM, 1GB+ ROM - Yes, but why?
So the target for JerryScript is machines in the Due range. Rust has been crammed into the Arduino Due, which may become a good approach for embedded work. Go probably won't fit; too much runtime.
They're all in the $25-$45 price range. The Due, surprisingly, is the most expensive.
To be fair, that system really doesn't run anything dynamic well.
However, your point stands. Requiring 64K of RAM puts this above most ARM Cortex M0 chips.
Picobit (https://github.com/stamourv/picobit) sits comfortably in 16K ROM/4K RAM. There's no good reason why Javascript vouldn't do the same.