I disagree. Amazon's cloud is great for getting started, no doubt about that. And yes, they take care of all the administration. But the hardware and bandwidth costs are absurdly expensive. Probably somewhere between 2x - 10x as much. Netflix is outsourcing it because they are rich and can afford the scalability that Amazon offers.
The mantra at every large company I've ever been at once we get past the initial "Get it done" phase, is, "Do it cheaper, cheaper, cheaper."
I think the thing that everyone overlooks when they price AWS out is they are looking at the cost of the bare metal. They aren't pricing their Network Engineers, their DBAs, their Storage SysAdmin, Their Data Center Ops Manager, the finance overhead required to buy/track all this gear.
Forget about the fact that no company over 200 employees I've ever been involved in could add 30-40 servers in less than 30 days.
The reasons to not go to AWS have to do with things like control, security, customization. Cost is the #2 reason everyone I've talked to is looking at moving their infrastructure over to AWS. (Ability to quickly scale is usually #1)
"Netflix is outsourcing it because they are rich and can afford the scalability that Amazon offers." - You honestly think that Netflix is getting an economy of scale from AWS? I think it works the opposite way. Perhaps they took the time to actually examine the hidden costs instead of using a calculator for 15 minutes on Tiger Direct.
