Not sure I understand the ding protection factor with these skins (or any other). If you go to a store, look at the rMB's backside and notice the dings. Bestbuy shoppers have complete disregard for display/demo units and you can easily see the dings on the backside, which these skins seems to expose.
Incidentally, this is the same backside area I once dinged my first MBA on the airplane tray table upon descent
I don't have a photo of the dings I saw at stores, but here are the edges I am referencing:
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