It's a brilliant design choice. At first I was like "What?" and now the more I think about it, the more I realize it is an absolute genius move.

People need to get trained out of (even informally) assuming they can identify someone because their username looks familiar, and this is a great way to do it.

> more or less completely eliminates “vanity names” and the “value”

With notable exceptions, i’m sure, being username69 and username420 and a few others (a similar phenomenon happened in magic the gathering, when they introduced limited edition 500 print runs of cards with the serial number stamped on them, and the only ones you can really sell or command a good price for are 1, 69, 420 and 500)