A great example of how all of this turns out to be good design is that you can see how easily UNIX-based systems adopted Unicode. Say what you like about byte streams as a universal interface, but it sure was easy to switch from ASCII to UTF-8 when your system APIs weren't all built around the idea that everything would be encoded in a particular way.
I don't think systemd is unpopular or controversial because it's a great leap forward. That's just buying into the propaganda. It's unpopular and controversial because it presents itself as a great leap forward while not being one.
>but some new OS will - and eventually that OS will supersede Linux in the way many people believe Rust will replace C++.
C++ hasn't even replaced C. Why would Rust replace C++? When has a popular, stable, architecturally-important language ever been replaced?
The sort of people that think that Rust will replace C++ are the sort of people who thought Java would replace C++, who thought C++ would replace C, who thought Windows would replace Unix and who think that another system of opaque proprietary object-oriented APIs will replace POSIX. They're wrong, in every way.