I totally agree about the invite nonsene. It's just a marketing scheme that attaches to some value to a free service.
I can understand why Google would offer a huge email inbox. They look at 2 gigs of email as 2 gigs of AdWords they can sell. I don't understand why other companies are trying to offer huge amounts of storage. If I was having to deal with 30 gigs of email I
would want to use my own mail server and desktop software to deal with it, not webmail.