It has a literal "run executable" button. How much easier so you think it could get?

But that just runs the installer. What about the program that is then installed? I remember this being a bit of a hassle, and not having a super great UX. It works, by all means, but it's just a lot worse than Windows, which is admittedly a lofty standard for exes.

After running the installer (or any exe) bottles scans the registry for certain keys (I don't know the specifics) and if it finds that new programs have been installed, it automatically adds an entry under "Programs" in the Bottles UI (which is under the "run executable" button).

You also have the option to manually add installed executables under the "Programs" section, or into the "Library" section (Library is global, programs is per-bottle-sandbox)