The problem isn't the dragging to the application folder itself. I've seen my mother do this and it went fine.

He problem is that the application isn't moved, it is copied. After putting a copy in the Applications folder, she just drags the application from the disk image to the dock. Now she has two copies, and uses the slower one in the disk image. Sometimes she even drags the disk image to the Application folder too. It's all very confusing

I agree that the disk image system is very confusing for the casual user. The zips seem to give a much nicer interface