I like the peace and quiet of a Sunday and I can't see any real reason why this would change if the law were to change. I think that is the main concern for having kept things the way they are for so long.
I believe that changing the law would create jobs and would potentially give people extra income. It would make working people's lives easier with more options available for doing the shopping, organising other activities, etc.
Different staff could be employed to work different days/shifts. People would on average actually gain freedom in their personal lives as a greater social flexibility would bring with it increased potential happiness and contentment.
I very much doubt whether a modern day uprising would happen because of religious concerns if the idea were to come to fruition if that is what has kept successive governments from taking the plunge. Besides, if some believe that it is their right to not work on the Sabbath, that can be accomodated in law and protected if necessary and yet give others the options that they too deserve should they want to work.
I dare say that the taxman would be happy with the idea, as the general profitability of the country would doubtlessly increase.