The negative rates are only charged by the central bank to the banks, not to consumers (because the banks don't pass the negative rates on so as not to alienate customers). So the theory is by penalizing banks for holding money by charging them interest to do so, they are incentive to loan it out instead, thereby creating economic activity and spurring the economy.
Which is why banks are speaking out against NIRP; they get charged and consumer demand is still on life support. Banks were borrowing at 0% and getting paid to store their excess reserves with the government. But the crux is that there is very little appetite to borrow to the level needed for a consumption driven economy. There is no recovery. That tide has gone out.
So the CB NIRP is the trial balloon for introducing NIRP to the public; once we get 'used' to the idea and the world doesn't end, it's coming. And NIRP won't necessarily mean people begin to spend, an example being the report in Japan that sales of safes have skyrocketed, pre-empting the move.
And I also hope that Bitcoin will have a great future and that many stores also accept Bitcoin.