> Network services are defined by the presence, in a directory watched by listen, of executable files whose name is of the form <protocol><port>.

That seems a bit silly to me as it means something like rot1376 is tricky to parse correctly. I'd think it would make sense for the protocol to need to be separated from the port by a non-numeric character, like a hyphen. Like that it would be trivial to parse: just grab all the numeric characters from the end until we find the non-numeric character.

Inetd style services are great, but do have an issue with programs that have a lot of startup overhead (e.g. things written in Python). I always thought the FastCGI approach was a neat one, with a defined protocol for what would otherwise start a new process, and the managing daemon can choose if/when to start and stop the process. It certainly makes the listening daemon significantly more complicated, and the actual launched program slightly more complicated, but IMO there are real benefits there.