> rather than a full alphanumeric password Because there are different kinds of keyboards out there, with different layouts, so if you switch keyboard you coul

> rather than a full alphanumeric password Because there are different kinds of keyboards out there, with different layouts, so if you switch keyboard you could find yourself unable to input the password. Imagine typing a "non-English" letter in the password and then switching to a US layout keyboard without that letter. Sure, a rare scenario, but with hundreds of millions of users you will hit it.