We are not living in a society where cryptocurrency is widely used to pay the bills. If anyone wants to use cash and anyone wants to use cryptocurrency as cashless then both will be considered for me as a customer and I have to give them my service with utmost priority. If the store owner is me, then I must set using both methods to pay. But I can't assure others thinking in this type of perspective.
If it is legal in the country, then definitely should be adding bitcoin as a payment option. In start might not be many would be knowing or interested in it, but with the spread of word and promotion being done as customers will be made aware about it, this will just be an advantage for the long run and obviously some would be there who would like to make payment in bitcoin and will come to store to purchase stuff for it.
Yes, the customer is the king. So they must deserve the utmost priority from the shop. If they want to pay in Bitcoin and the country already legalized it then there has no problem with Bitcoin as a payment gateway to pay for the needs so that both parties can feel better. Small try can change the whole scenario.