Why do those require a single executable?
I deploy exe's often, and to many inexperienced users.
They will run the applications directly from zip files if they can, because they often will not now the concept of unzipping. To them a zip folder is usually just "a funny looking folder".
The concept of installing,running and uninstalling an application, trivial as it may seem to most of you, is not always an easy task for some of my users. Running the application for the first time may work, but refinding the shortcut and starting again is another matter.
It's a huge timesaver for me not to have to create setups.
I'm sure I have more reasons because I've been over this so many times in the past, but this will have to do for now.