Or people like me that are stuck with AT&T so a contract extension is meaningless. Also for each release AT&T has allowed early adopters to purchase the new model with no upgrade penalty.
When the iPhone 4 was released I sold my iPhone 3G for ~$250 and got a new iPhone 4 for $200.
When the iPhone 5 is released I can sell my iPhone 4 for ~$250 and get a new iPhone 5 for $200.
So yes, I'd like $50 and a brand new phone.