This new feature is only working to those who use coinbase but if you are sending BTC from coinbase to other client or wallet you will still need the long BTC address to send BTC.
So this feature is only restricted to coinbase users. Not a good one for me, as I can send btc with other addresses even though its traditional method. It just an upgrade but the effectivity is restricted to their users.
Take note, that many countries arent even allowed by coinbase to register.
I guess the long hexadecimal nature of addresses also add in some bit of anonymity to people using them as they are not forced to use regular usernames that can easily be connected to individuals.
I still prefer the hexadecimal address and having username can also be a confusion to other users with mostly almost username. I remember eos blockchain in this idea, which confuses some due to difference of one letter or number and could end up sending to wrong person.