Few reasons, some less valid than others.
Computational theory would be a better name, but it overlaps with a more specific subset of what is normally called CS.
My CS program had virtually no programming outside a couple of courses where C was used to implement concepts. Had one applications type course where mostly Java was used.
CS is and should be a specialized math curriculum IMO. Teaching specific programming languages is time that would be better spent teaching theory that can't be taught by dev docs or code bootcamps, as exemplified by your anecdote. Unfortunately nowadays people tend to see degrees as glorified job training programs.
Depends on what you're doing in your config and what you're changing. My configs are huge and complex because I was a moron when I first started out. Adding packages to your nixosConfigurations is a smell IMO. Most of the time, it would be preferable to add them to a devshell instead.
25 seconds sounds pretty close to my experience, but my machine is beefy and my configs have a lot of bad patterns for eval time.
OpenLDAP does.
There's not much to replace GPOs, but you can conditionally provision most settings on NixOS. Would be nice to build an MDM around Nix.