Obey The Hypnotoad!
I don’t like the username decision but it didn’t seem hostile to users. People seem to pick a username, update their server profile, and move on. My account is old enough that I picked my username pretty early in the process though.
I agree that casual users likely found the discriminator confusing, though I never verbally shared my username with people. It didn’t seem like a strong enough reason to warrant the change.
Why do you consider it hostile? I doesn’t seem like it has degraded the overall experience.