I was actually waiting for your reply saying that I had missed the point :-). I think that automatic line numbering (as an example) misses the point of the UNIX tool philosophy, namely composability. It would seem that the designers of grep and nl thought those were separate tasks. The point of the CLI is that you can make the simple building blocks do whatever you want, for any workflow. You can always make an alias for grep that does numbering by default.

Basically, however widespread our personal workflows are, there are vastly more workflows we havent't even thought of that are essential to someone else's livelihood, for whom automatic numbering (or whatever) would ruin everything.

As for source maps, yeah, that's got room for improvement.