I could see if you wanted to sell you vehicle and you just couldn't give a shit that you defraud the buyer and possibly put his life at risk, but I can't imagine (as cheap as I am) doing this to my own car.
There are a couple rub spots on the covers
yeah, where they slammed into your face when you smacked up your car
Its interesting that these are 'loose' covers. Most IPs have weak lines moulded into them around three sides of the airbag module. When the airbag fires, it tears the IP along these three lines, the fourth side becomes a hinge. This is to retain the airbag cover. If there is a loose cover over the airbag, when it fires, it blows the cover into the occupants face.
Bit like the Air Guitar add that some wag submits every week and thinks its hilarious, someone who obviously wasn't a member of ebay the first 15,000 times a similar add has appeared. The odd thing being they often attract bids.