This is a great option for UX. Here's a fun old post from 2008 (from a former co-worker) on a similar topic: https://almaer.com/blog/its-just-my-email-password

You do want to make sure you add enhanced security around changing an account's email address (make them log in again, for example). The analog is forcing people to re-enter their password when changing their password in a more typical username/password system.