One part of the explanation is that these are the same folks that often deal with the small politicians and exploitative moneylenders - so now, seeing these corrupt people suffer greatly from this move, they're full of heartfelt praise for the central govt. At least half the praise I hear has been in the form of "you should have seen that politician's face" or "that moneylender is roaming all over town trying to change his black money".
It might be very sad to say but a lot of these shops exists because of the black money. Some are mere shopkeepers whose owners would have opened these shops to invest their money. Now think what would happen when their cash gets sucked away. There would definitely be a huge loss of jobs.
If real estate is hit badly then a lot of laborers would be jobless overnight. A lot of projects would have to be stalled.
Presently there is an uneasy calm and some sort of schadenfreude but when the dust settles the consequences will not be good.
You need a bank account for this process to be convenient and easy. Without it you have to exchange in bits and pieces.