Blame 'Murica's brand of capitalism. =p (Partially srs.)
As a culture, we've learned to automate things more and more, and we call it "convenience."
As a culture, we're constantly inundated with advertising messages to consume, consume, consume. Portion sizes have progressively gotten bigger, HFCS is in practically everything, and inexpensive, nutritionally questionable food is everywhere, from the microwaves at home to the microwaves in fast food restaurants.
Is it really a wonder why the US leads the world in obesity?
We need a culture shift.