I would like to but it's slippery and just takes one bad luck moment to take a hard fall and crack the brittle glass. I don't like bulky cases either so as of now just settled with the case it came with which offers some protection against light drop/fall.
The nice thing about having to use a case is, it's a treat to see it naked.
Dang it, just dropped my U11 from about waste high without a case. Thankfully no damage but scared the crap out of me. One minute it sticks to the palm of my hand where I can nearly turn my hand completely vertical without it sliding off, the next minute it like trying to hold on to an ice cube. I hope to God my cases I've ordered from Amazon get here today.