Hard to believe this can't be turned off. It should be under "PC & Devices > Corners and Edges."
I'm not a fan of the look either, but for me it's a functionality issue. I use metro Remote Desktop constantly from my Surface RT to log into my workstation. My workstation is usually on desktop mode, so imagine my frustration that every time I use my mouse to go to the top right corner to close the program I'm running on the remote machine, I inadvertently close Remote Desktop altogether instead. SO MANY TIMES EVERY DAY! AAAAGGGHHH!