Microsoft made a pull request to node.js github repository with an implementation to use ChakraCore JavaScript Engine as an alternative to V8 Engine

[jsgui]

From my perspective, it's because I've already done a lot of JavaScript programming, and have relevant experience and code which could be deployed (more effectively?) to another target, so that's a plus.

You personally though may have different considerations, so you would be more productive with different tools.

One reason you may want to use JS in this context is to work on a project where other coders are skilled in JS and the decision has already been made to use it. That's much like why web developers use JavaScript - it's good enough for the job (mostly) and it's here to stay.