My guess is that when you call them on the phone, they ask for your password to validate your identity. Which means it's stored in plain text in their database so that customer service can verify what you said is correct. Maybe they don't want their employees to have to be cursed at by customers.

I can't think of a good way for a business that has an online interface and frequently handles phone calls from customers to validate that they're talking to the correct person. Asking for other personal information can be used by an attacker to compromise multiple accounts via social engineering: http://www.wired.com/2012/08/apple-amazon-mat-honan-hacking/