If you're using AWS then Cloudformation (maybe with an abstraction like troposphere), will do what you need.
If you are pressing the big blue 'launch instance' button, you are doing it wrong.
Agreed. Advantage is clear and understood.
My point here is: there exists something called 'Amazon Console'. I argue it is a good thing to have if done properly easing the service management as visualized management is more human friendly and APIs more computer friendly. If there exists a bad visualized service management (e.g. Amazon Console) it is the lack of skills of the humans developing it not because managing a vast complex clusters is easier through APIs/CLI and impossible/wrong via UI.