You're missing the simplest explanation: during his campaign, Obama lied.
Dead on.
Obama learned politics in Chicago - the current record holder for corrupt big-city political machines. He is a classic example of a corrupt machine politician.
The Clintons are also masters of the (less intense) state-level version of the form, having risen to the top in Arkansas, which has been run by a corrupt machine since a Mafia family from New York took it over when the big city got too hot for them. Obama beat them for the Democratic nomination. He has now remade the Federal government on the model of Chigago.
This was predicted and announced by quite a large number of people well before the election. Nevertheless, he won. So how did this come about?
There are a number of factors. But IMHO this is the most decisive: The Republican Party's organization, for well over a decade, has been solidly controlled by the Neocon faction (one of the four major and several minor factions of the party). In the last two presidential nomination battles, the Liberty wing (another of the big four), under the inspiration of Ron Paul and drawing members mainly from the young and/or Internet connected, made substantial inroads.
Their successes in the 2008 nomination process threatened to eventually displace the Neocons' control of the party machinery, as the Neocons had displaced their predecessors (mainly the Christian Right) previously. So in the 2012 nomination the Neocons fought an extremely dirty battle, with large amounts of cheating, rule-breaking, and even incidents of violence (including broken bones). This so alienated the Liberty wing (and some members of other factions) that they refused to support the Neocon's nominee in the general election. Romney lost five states by margins substantially less than the number of people who voted for Ron Paul in those states' primaries, and those states' electoral votes would have swung the general election. It's a good bet that virtually none of the Ron Paul supporters voted for Romney, and even those would have been more that balanced by Republican voters for other candidates who were also appalled at the machine's treatment of their opposition.
One circulating meme was: "If this is how they behave in the nomination process, how can we allow them to control of the machinery of the Federal Government?" Even KNOWING that Obama would run the Fed like a Chicago-style machine and use it to stomp on the people, letting the Neocon's machine continue to consolidate their control of the major opposition party and drive the big-government non-choice-election system into the foreseeable future could still look like a worse choice.