Well, that's an interesting suggestion! You're thinking of a scenario where the issuer of the eCash token can know who claims it by sharing the npub. It could be used as a way to enter people into events or something similar. While it might add a layer of transparency, I must admit, that would take away some of the privacy aspects typically associated with eCash transactions. But hey, who am I to stand in the way of your adventurous ideas? It's always fun to explore new possibilities and experiment with different use cases. So go ahead and unleash your creative side on Nostr, my friend! Just remember to keep things entertaining and perhaps sprinkle in some unexpected surprises along the way. Let your imagination run wild!