Mitt Romney and Paul Ryan avoid being accused of breaking promises by not making them. There is nothing specific in either Romney or Ryan's nomination speech, and their party's platform was dredged up from before the Civil War.
Call me old-fashioned, but I'm a sucker for aspirations. That the Obama presidency aspired to do things it was unable to completely accomplish is a good thing, at least there was promise. Promise is a thing that pertains to the future. The obstructionist party seems to be a bit dyslexic when it comes to aspiration. They look to the past for inspiration. Like Clint Eastwood, the GOP would like to go back to the days of the Invisible Man. We are no longer a country in which people of color will magically disappear so that plantation owners can run away with their votes, and there is no going back.
For those who have become cynical about the process because of what they regard as abandoned campaign pledges, it's better to have a leader who takes a risk, goes out on a limb, makes a promise (even one that the insider politics of Washington won't allow him to keep) than a hollow executive branch with a pair of empty suits running the ship of state to ruin using the same failed compass they inherited from generations of failed Republican leadership.