There are many reasons, but there are many millions who believe is just doesn't matter. Most of us here well understand that it DOES matter, and that the damage Ryan and Romney would have done by now would be vast. But that doesn't change the fact that Obama is mostly about good speeches and keeping his nose clean so that Barack Obama will have a legacy as a noteworthy President. He just doesn't care very much about the things that used to be known as "core Democratic principles."
I don't really know what point you are trying to make, as these things are self-evident.