Revert the username changes. I paid for my username for over 8 years and have lost it to a squatter because of this dumb policy. There are many threads about this already and there should be many more. You have lost at least $200/yr in subscription dollars from me.
My account was day 1 Nitro, registered in 2015, and I had the same username for OVER EIGHT YEARS. Why you decided to take that away from me is beyond comprehension. Your reasons for the change are, as many have pointed out, spurious and ingenuous. Revert this.