I think EIAF is an incredibly elegant solution to a problem that only became really relevant decades later. I cannot believe how people are actually programming systems which expose super-simple stuff via complicated syscalls and other APIs. It is (one of) the basis for the effectiveness of shell-scripting, one of the huge benefits of UNIX, enabling easy access to the heart of the machine, both soft- and hardware. It promotes choice of tools, because there is no need for elaborate client-side libraries that need to pre-exist.