Are you still looking into bringing back this basic functionality? 6 months later and as far as I can tell the situation with selective "fill-only" (when "fill and submit" is the default) and updating an existing login remains unchanged?
Maybe I'm missing something, but I still struggle with this frequently and it 1Password has dropped way down on my list of favourite apps. I'm about 2 seconds away from trying out a competing app purely out of frustration.
My password database has become filled with duplicates and half of them are named after the domain name and the rest after the title tag or some other guestimate, so half of my duplicates dont even appear next to each other anymore. And 1Password makes it so hard to clean this up, it just ends up getting worse and worse.