The inability for Obama and Democrats to build a positive narrative out of their accomplishments points out a major flaw in the DNA of American politics.
It seems that the Dems always want to play the role of compromisers, but by playing this role accomplishments such as Healthcare or saving the economy of the western world end up obfuscated and confusing to the public.
Why are we such compromisers? Because the alternative is to stand out, move Left and be called Socialists.
For Republicans the opposite is true. When they move to the center they are excoriated as moderates, but when they move to the Right they are called Patriots.
In Europe they'd be called Fascists, but our history and DNA doesn't allow for that.