>There are lots of useful actions an installer does that (some, if not most) end users actually want, including but not limited to adding shortcuts to start menu so you can find it or search for it, associating file formats, registering to Windows' program list, etc.

This, I don't really mind unzipping some random small utility, but for things like games and larger applications where you'll actually be saving data and preferences, a real installer that knows how and where to put things following the correct methods for the operating system is much preferred. Then I can run the uninstaller to clean it up when I'm done with it.