They will have to consider that bitcoin have a price that is too unstable. It may cost their business to go down or maybe up but that is a risk.
In business, they would always want to minimize that risk so that it can stay for a long time and bitcoin doesnt fit to that yet.
Those are legitimate concerns for a business, but not applicable if you know how. Businesses use a payment processor to handle electronic transactions like credit cards. If they want to avoid price volatility and handling bitcoin then they can simply use a bitcoin processor like coinbase or bitpay. I have helped businesses set up a processor and it is very easy. Once they are set up they can take bitcoin but not touch it. The customer pays with BTC then the processor sends a deposit in dollars to their bank account. It could not be easier and is cheaper and faster for the business than a credit card. There is no logical reason to not take bitcoin. It costs nothing to try and can earn you more when a customer pays with it.
Of course no retailer will do this unless you