Ultimately that's a job for the designers though. The coders job should be to just implement what they're told in a robust performant, but also pragmatic way.
Exactly, they have appeal to people independent of technical skill; hence my hypothesis that they make sure to emphasize the things that are more likely to resonate with larger groups of people (like emoji) rather than things like Project Treble or a "native C/C++ API for high-performance audio", even if the former really have little to due with the OS itself.
If we're going down that route, it's also worth noting that "old people" such as GP referred to also can like emoji; my parents and grandparents enjoy using emoji.
I don't know if I'd say its a mess. There are three options that are well aligned with emerging trends: Plex, Emby, and MythTV (to a lesser extent). The rest have a lot of catching up to do if they want to remain relevant.