When adding a new password to the mobile app or chrome plugin, I'm frustrated that I have to manually type a username, when for the vast majority of cases the username is one of my email addresses. This is particularly a problem on mobile, since typing an email address is difficult.
My expectations would be:
in the iOS safari lastpass popup, when typing into the username field I would expect the keyboard to suggest my email addresses like it would on an email field in a website, and/or I would like to be able to select one of my email addresses from a drop down on the username field.
in a large-screen web browser, i.e. using the chrome plugin, I could select one of my email addresses from a dropdown in the username field in the little popup that appears after submitting a new registration form.