When I'm trying out a new language and writing programs in it that I'm going to invoke from the command line, one of the first things I do is put in those BSD-style extended error exit statuses. I also check along the way whether whatever option parsing library I'm using integrates at least EX_USAGE by default; the answer tends to be no, though I'm not sure how much of that is the library authors not knowing or intrinsically not considering them appropriate, and how much might be “new users will see this behavior, decide it looks complicated or bizarre, and leave”.