It's like browsers all over again. As long as each provider is offering different things or different implementations of the same thing we will either need to choose one or be forced to go through a lowest common denominator translation layer.
MSFT, GOOG, and AMZN are all smart enough to not turn this into a race to the bottom of who can provide the cheapest scalable instances. They'll all try to differentiate on features and so it's going to be a long time until you can treat these as a utility.