You would have real fun when one of your running instances shuts down on it's own (and possibly comes back after some time), and would be pointed to the AWS SLA upon asking them what had happened.
You would have more fun when rebooting an instance would take 2 hours to be told that there was some underlying issue with the hardware.
For samples of the responses that you get from AWS:
Or you could author software and systems that aren't so brittle that the loss of a single machine is problematic for you. Seriously, your engineering practices need some love if this is a problem.
Does that imply that every single webpage in the world needs to be behind a load balancer with unwarranted amounts of redundancy in place?
And if one doesn't do that, it's ok if the site is down.
In fact it is worse: typically you are resource constrained as the budget cycle to buy new hardware doesn't start up till next quarter so you literally don't have another machine to run on so you are screwed.
That isn't to say that AWS is without fault, but I find most comments about unresponsiveness of systems or the inabaility to find a route cause (i.e. A bad disk) would happen anyway with another system designed in the same fashion.