I don’t save my important passwords in any password manager. This includes passwords for any financial website. I do want to save my username for these sites because it is frequently 16 digits. Maybe I relax my standards and I add passwords. That’s easier when the entry already exists in password manager.
While I understand it’s a “password” manager and not an auto-fill manager, it seems like it would be easy to implement and at least one of your competitors allows me to save a username without a password.