"Simple" means different things to different people.

Apple aims their products at individual people. "Think Different" means "Don't think about your computer". So write your book, keep your spreadsheets, whatever. The user doesn't care about the computer.

Microsoft, in contrast, wants to keep the CIO happy. So you have robust single sign on, reliable and modular patching capability and backwards compatibility. IT cares about the computer.

Open source projects are all over the map. In general, current Linux users are enthusiasts. They WANT to customize Emacs macros and tweak their operating environment. The user cares deeply about the computer, and gets some amount of joy out of futzing with it.