1.) It's less secure (unless the email is encrypted, which in most cases it is not).
2.) If you use GMail with several accounts and POP3 you'll have to wait until GMail sees fit to fetch the email.
3.) Password managers provide both a superior UX and superior security. So, by all means at least provide a password-based login as an alternative (which admittedly defeats the purpose for the operator to have a less complex authentication system to worry about).
1.) It's less secure (unless the email is encrypted, which in most cases it is not).
2.) If you use GMail with several accounts and POP3 you'll have to wait until GMail sees fit to fetch the email.
3.) Password managers provide both a superior UX and superior security. So, by all means at least provide a password-based login as an alternative (which admittedly defeats the purpose for the operator to have a less complex authentication system to worry about).