It would be great for this to be implemented. Just like how you can create a new Bitcoin address for every transfer, you could create a new key for every Nostr login, while keeping your actual nsec private and secure. As it works currently every login with your nsec is like typing in your 24 word backup into Internet connected software. There is a lot of trust involved there. If you could create keys with the possibility of invalidating them if a client app goes rogue it would get rid of that trust issue.