Negative rates are scary if they go low enough, where an inverse of the problems with high inflation come about. Rather than try to collect payments as fast as possible due to the eroding value of money, there will be an incentive to delay receipt of payment as long as possible. Taxes will be overpaid to be reclaimed in the following year. How would your local telco handle being treated as an implicit temporary checking account?

I don't claim to understand all the implications, but it's an odd experiment we would probably be better off not trying. What's worse, how do we ever get back to some range between [-2,2] once we've gone that far negative?