I'm not so sure most people would agree with you. Though I think plenty would.

I dare say that developers like environment variables more than before. Consider that Docker images, and hence Helm charts, are entirely controlled via environment variables. These very popular dev tools suffer from the same problem of having near-zero easy discoverability of what those environment variables might be. Yet they are very popular.

But I don't think Make usually uses all that many environment variables. You're usually specifying build targets as the command line arguments. Automake and autogen usually generate these makefiles with everything hard-coded.

Also, it makes it very easy to get started with, and it is universally available. Makes it very easy to like.