Touch-based (and by extension, NUI-based) OS'es and mobile applications are the future. Windows always sucked. Mac OS always sucked. Every desktop OS ever built sucked because it is a horrible way to use a computer. Nobody ever really wanted to use these terrible desktop metaphor systems... they only ever did because they had to.
I guess the desktop environment was just a random choice of "this works, so just leave it in" from whatever distribution they started with.