When you're trying to use Google Apps for business, for one, and you go to email.MyURL.com and get redirected to a standard Google login screen where you now have to click a button to not sign in as your personal account, then come back and sign in as a business account, plus also add the "@MyURL.com" at the end (didn't used to have to do this), and you're doing that with multiple different accounts, it gets pretty tricky pretty in a hurry.

An extremely common use case is to have several google accounts, typically when using various Google Apps domains.

Instead of understanding that I'm the same person with access to all of the accounts, it makes me log into each one separately. For most products you can be logged into each one simultaneously, but the first one you log into is the "default". Analytics, for example, doesn't even support multi-login, so if that "default" account is not the one you want, you have to log out of ALL of them. WAT