This has always been my thought. It all depends on who we want to join the Nostr community and the odds of the app being their first experience. 

My family members don’t need to see what or where JSON or NIPs are before finding and providing value in Nostr.

I will say though that while I believe there is a place for apps that do not expose keys to the user, this should be the thing that is made most likely to be learned by users on signup and shown to users throughout. There are so many Nostr apps that do not adequately explain the importance of the private key and the need to securely back it up.