On Amazons "Black Swan" day, there will be on new instances to fire up. Your current instance and all of its data may well be lost. Your little account will be the last thing they're worried about restoring. EC2 is great for startups, but when the time comes, you need a multi-homed, multi-located setup you've done yourself so you know what risks are involved.
Who's to say that Amazon hasn't deployed a "multi-homed, multi-located" setup, or that yours would be any more reliable than theirs?
I don't necessarily care about knowing all the potential points of failure, especially if I believe they employ people who know more about the equipment than I do. You could argue that the only reason to build your own data center is if you believe you can do it better than Amazon, if of course you can match your architecture to their system.
