Because right now - the Beta opens up to me this evening and I'd rather be playing it than faffing about installing Windows 8 lol. I doubt I'll have enough of a performance issue with W7 to worry about it for now.
Plus a fresh install of 8.1 is probably more advisable.
That's what im going to do i think. First i need to see what happens with the 8.1 update. I will install it to see how it done. Then i'll likely reformat and start a fresh in anticipation for BF4 launch.