That's exactly why I put a case on mine. The Kevlar is stupid and makes the phone incredibly slippery. I bought a Cruzer lite case which didn't add any bulk.
Screen protectors show more smudges and cause more drag when swiping across the screen. Just wipe the screen with a soft lint-free cloth or on your pants or shirt.
It's honestly the first I've heard of the issue. I'd still chalk it up to a fluke or a wonky device, though. There is too much support for the pro crowd. The GNex on Verizon has always been a problematic phone, a sort of red-headed stepchild.
Unfortunately you are the first and only person that I've heard of with that issue. I allow Google Now to update my location and my battery life is still stellar. I've never seen anyone else disable it; most rave about it.