I was actually shocked to know that you can use Bitcoin in stores. And you also mentioned that the transaction takes a bit of a long time. However, it must be noted that not all people have the resources to have Bitcoin in their hands. In some countries just like mine, I think using Bitcoin to pay for groceries or small items is not yet possible. This is due to the lack of access of people to have Bitcoin within their grasp because most Filipinos belong to lower classes. So I think shopping centers, malls, or stores would lose profit if they would rely on Bitcoin used by only few people. Another thing is that, despite of the fame Bitcoin is earning among people, few believes its genuineness.