THIS is what 1Password is great for, and I'm 100% with you on using these types of features.Switched 99% of my usage to Apple Passwords, but I still use 1Password for:
1. Storing credit card info securely, in a way that I can easily access for reference. What's the best way to do this without 1Password, encrypted/locked Notes?
2. Sharing passwords as a one-off, rather than creating a "Shared Group" in Passwords. Any good alternative here?
BUT...
The things Apple Passwords lacks, would be SO easy to implement into the app, but it's either just Apple-laziness, like most things they do these days.
Or, they don't want to compete directly with the app makers in the space (not that Apple typically cases about stealing entire segments - unless 1Password is a worthy-enough opponent and/or has enough Mac users that Apple doesn't want to lose them). That's the only other reason I see Apple not improving Passwords, however it'll probably stay exactly as-is for another 5-10+ years at Apple's current development pace for most of their apps.
But if Apple just added a few features to their Passwords app, mainly if it had just added another type for "Secure Notes" (heck, even Keychain has this - why not Passwords?), it would be about 50% more useful than it is right now.
Other types as well, but just a place to park Secure Notes = Apple Password's biggest weakness in my opinion (But totally use the features from rweiser that were quoted and wish Passwords had it all).