Best cover I've ever owned.
As far as "what is the purpose"... It's a beautiful cover, several layers of leather stitched together. So if I did accidentally drop the thing, there is at least some bulk there to hopefully absorb and cushion the impact.
As far as the keyboard having some "bounce", it is true; and that's my ONLY issue with the case. Most of the time that I use my Surface, I have my computer bag with me. So I've solved the "bounce" by keeping some of these (felt pads -
Shop Waxman Brown Round Felt Pad at Lowes.com) in the bag, and placing a couple under the keyboard when I'm typing. I don't STICK them there, just place them there. They are small, discreet, and do the job perfectly. "ghetto"? Yes, but a 5-second solution to the only thing that nags me.