Thing is, most normal users do not care about the settings. They use the computer like a TV, turn it on and expect it to work.
Nothing is stopping power users from looking through the settings to find good things to tweak, of course, but setting weird defaults to make a user look at their settings is indefinitely worse than, say, an optional tour of the OS that greets the user on their first login.
I mean, yes, you can do that, but then that brings us to the question: why does the user have to do that, spend a lot of time changing settings to make an OS bearable? Imho, any OS should ship with sensible defaults that have the user in mind.