My main argument is that a big part of our userbase is now using Damus as their only interface to Alby. So it makes sense to show those users their balance in Damus to have a more wallet-like experience. I don't know how Will will implement it but it will probably be fetched when opening the wallet tab that they have.
Discussion
Having the NWC interface is good and people should feel free to code it. I just don't know if it's applicable to Amethyst yet.
Maybe this creates a new class of Nostr-native Wallet apps. Who knows..