In fact, I also thought it would be fun if it was possible to use JSX in B.js, but I would also like to have concepts like hooks. In general, I would expect concepts from the React world.
JSX and React are very popular, this is already a certain standard for the web-dev and if the same concepts could be applied to a microcontroller, then it would be fun :) Also, in theory, it would add popularity to the project, new users, because the world of React is huge.
However, there must be a person who will do this: create and maintain JSX React transpiler into the Espruino JS code. As a plugin for Babel or something else.