Well that's a great feature and smart of developers to take advantage of. But what I am really curious is the thought process (if it's possible to remember and elaborate on) for someone who was going through this the first time, was not presented with such a user-friendly DMG background image, but was still able to intuitively figure out what to do.
It seems to me that while it might be a great way to install something - incredibly simple - years of Windows use would completely program someone to not consider something so simple.
It's not actually simple - that's the key. The alleged simplicity is an abstraction, and most PC power users are more familiar with the underlying mechanisms. Efforts at hiding these mechanisms are all well and good, but if and when something breaks, or you need to do something unorthodox (e.g. automated installation - many setup.exe's take a '/?' flag - or moving installed apps from one drive to another, etc.), lower level knowledge is needed.
It seems to me that while it might be a great way to install something - incredibly simple - years of Windows use would completely program someone to not consider something so simple.