As some already says and the few i've seen on Windows 8.1:
Reduce dependence on online services & social networking
Make updates & Patches available outside
No Windows OS subscription based
Make it easier to run the system without having to connect to a Microsoft account
Surely some security based settings, boot option, too.
I do not mind too much the Modern UI and its flat color design, well, i could get use to it but will a start button and programs list added along the one Welcome screen too.