Google's mission is "to organize the world‘s information and make it universally accessible and useful."

Gmail helps my company organize our email and communication, and makes it accessible from any computer anywhere in the world.

S3 helps my company organize our information and distribute it around the world.

S3 helps dropbox organize their users information and make it accessible from any device.

An S3 clone is clearly within Google mission.

Google's mission is also to make money, companies make money by focusing on their core strengths. I would rather have Google not clone other people's products, Microsoft did that and they failed over and over again.

S3 may help you organize your information, but that information is probably not public, and if it is then Google's services can access it anyway - they also aren't a charity - if you're looking for charity (i.e. products released for the betterment of the world only) then you need to search for non-profits.