I think he's using "big buttons" as a shortcut for the difference between highly rich, detailed interfaces which present many options all at once, and more "sim

I think he's using "big buttons" as a shortcut for the difference between highly rich, detailed interfaces which present many options all at once, and more "simplified", more intuitive interfaces which present fewer options, but where more work has been done to ensure they're the options you really, really need. At least, I hope he is. This is Ballmer, after all.