I think both of my current ones have built in (crappy) sound and both HDMI and Display-Port inputs.
Also, that feature you mentioned, while it works with some RCs (generally "source" or "input" key), doesn't take into account all the inputs which I am not using. So I need to go through a list of 4 or 5 devices including DVB-C cause yeah my monitor has that support even though I've never used that input. That's annoying.
It gets annoying the more often you gotta switch. For employees of government (like the mentioned example of the Pentagon) that's gonna be more often than not. Any downtime is then a waste because even if its merely 20 seconds back and forth it quickly adds up.
It could even make sense to have KVMs in businesses where they want to keep certain data strictly internal. But as long as companies aren't being punished for data leaks that doesn't have priority. Perhaps we'll eventually see a rise again of KVMs.
> "a person with whom one shares an intimate relationship : one member of a couple"
One can use "spouse" or "significant other" to avoid the perception of being passive-aggressive.
Practically, it saves me from having to use another set of speakers (you would not use 2 sets of speakers at the same time and I usually use headphones) and it also saves me from having to have or use 3 monitors which takes up more space and costs more.
My partner doesn't use her computer a lot. When she does, all the hardware is available for her. I use the 2nd monitor during development, gaming, watching movies, and RDP session.
As per some comments, I don't see how a VM would replace this use-case but I do understand its niche. Still, it saves us space.