Be pragmatic.. use the best tool at your disposal that suits your larger environment. If the company you work for is all .Net, they bringing in a small utility app that uses Python is a pretty big risk. The same can be said for most things in a given environment.

That said, I gave node a beachhead into a number of projects, because they were web applications and it made sense to do so. Even if not running on node, having the client-side bits using node tools made sense.

It really just depends. All in all, there are at least a dozen options for any given problem, and 4 out of 5 times the closest thing to what you are already doing is likely the right answer.