I’m not happy with everything about passkeys either. I am fine with them as an additional method, but I would never use them as the only method.
That said, I had a much easier time getting my kids onboard with a FIDO2 security key than I would have a password manager.
Enter your email and touch this is easy to understand.
One thing it enables is being the sole credential, as in, not needing usernames. It helps with faster logging in and is not prone to security issues caused by browser autofill.
This also means sites can allow you to sign up without collecting any more info than registering a passkey, but of course they want to siphon all that data.