You have to write software to do anything, anywhere. Strictly speaking, with Linux you need to write software just to have a GUI. All of the "trivial things" you can do with your computer are things people wrote software to allow you to do.

OS X is completely Unix-based. All the things you can tweak are things I can tweak, too. I can also treat OS X like Linux if I want to: Getting Gnome or KDE to run on a Mac is really easy. I tried it out by downloading Amarok, which was a huge mistake because the lack of polish in KDE shines through when it's next to Mac stuff.

(I can make an argument about why closed source is a bad thing, but it would be rather lengthy. I'm assuming you'd rather me not derail this thread by providing it?)