Maryland is more urban and has a larger minority population although Delaware is large too. Never mind if you compare to 2004, Obama still did much better than Kerry in both Delaware and Illinois. The 2008 results were anomalies so I think you saw a return to more normal results albeit on the high side for the Democrats in both states. I think a better question to ask is why the GOP did as bad as it did in Massachusetts (Romney's home state), Michigan (Romney's birth state), and Wisconsin (Ryan's home state). In both Michigan and Wisconsin, Obama did better than both Gore and Kerry despite the fact the GOP ticket in those two had no connection to either state.
Well, culturally Mitt was a horrendously bad fit for Michigan and he hadn't lived there in decades, so that isn't surprising. Mitt lost MI for the same reason Bush Jr. lost CT. In another world where Mitt returned to Detroit, made his fortune in cars and was a lead mediator in the auto bailout, he would have easily won Michigan.
New Hampshire is slightly more surprising, because Mitt was the best fit there of any of his home states. I think this is more a matter of the state just trending D. If you look at the rural areas in the western half of the state (NH-02), they are moving like Vermont did last decade. Mitt did well in wealthy suburban areas, but "East Vermont" was just too much to overcome. I think you will see Republican nominees increasingly ignore NH from this point on. It's small, out of the way and an increasingly tough nut to crack even with the right type of nominee.
In the case of Wisconsin, the bottom of the ticket increasingly doesn't matter much. Add to that some things that Ryan had done in the House that were fundamentally spooky to economic progressives and you have a problem.
Massachusetts is more curious, because Romney does have the right profile for that state as a Boston venture capitalist. His problems here were similar to Gore in TN. As connected as both were to their states, they had strayed fundamentally too far from the dominant local values.
In short, this election has basically told us that it is utterly impossible for pro-life, anti-gay marriage candidates to compete in New England.
Massachusetts isn't that hard to figure out. His presidential campaign rhetoric ran like hell from his record as governor there, and he never failed to bash the state while disowning Obamaca....er, I mean "Romneycare".
