IMO, including those generated .txt files is a small[ish] feat that's important to those that are looking for it, and benign to those that don't need it or know what it is.

I suspect most users who use a site generator would be happy with more "automagic"—especially if it were 1. easy to config or turn off and 2. addressing important things like security-related contact info, or how a web-scraping bot should respect your domain.

Also: "simple" generators often veer into "complicated" territory by adding crap features. Elegant appears to lack crap features; IMO, adding *.txt would not complicate or confuse.