Same here, I've only been using it for a bit and have 100% been ignoring the JS part and the only time where I felt I needed to think about it for a moment was when I was writing a patch for someone else's code that did not ignore it, so basically when contributing to a library you might have to do extra work.

Of course I can't say if anyone ever made any decisions based on the other target that would have repercussions for me only using the BEAM.