Not sure that's a good idea, as it lets people create their own giftcards by mining coins. If a company make a cryptocurrency that isn't accepted anywhere else, they essentially end up giving away free stuff.

Getting paid for a good or service with USD is useful because you can spend it to cover your expenses. If Overstock made OverstockCoins instead of accepting bitcoins, how do they pay their suppliers?

I guess that's more or less what Ars is doing, but I don't see how it makes any sense.