Installing and managing programs is an awful experience on desktop environments. I want something akin to mobile apps, where you have a central repository of programs you can just pick from and the OS will take care of installing and updating the program for you. Programs can only be installed in one location so there's no security issues, but they can be installed as sub modules of another program so you can still extend things.

Bonus: you know what's installed and you can access it from anywhere, without worrying about fiddling with PATH variables. You can easily deactivate or uninstall something and know it's been cleanly removed. Also, allow unregistered installations like with APKs that act exactly the same just without finding them in the search, and you're sorted. Perfect environment.

@Fenreliania
That problem is completely solved by package managers.
Since the '90

@pasqui023 they are close, but they don't keep programs installed in one common directory, they don't give me an easy clear list of installed programs, they don't auto update or even really let me know there are updates available, they largely don't seem to have any good GUIs, and they don't support a bunch of other little features I'd like.