Look if you thought Obama was all things to all people you were naive. If you thought sudden dramatic change was possible you were ignorant of US history.
Change can and does happen in the US but it takes a long time. This is somewhat by design as our founding fathers wanted checks and balances which acts as a hindrance to change.
Slavery wasn't made unconstitutional until the ratification of the 13th amendment in 1865. This overturned the Dred Scott case which decided slavery was constitutional in 1857.
Jim Crow wasn't effectively made illegal until the Voting Rights Act of 1965.
Women were not given the right to vote until 1920 with the ratification of the 19th amendment. This is some 70+ years after the birth of the modern movement for women suffrage in the US at the Seneca Falls Convention in 1848.
Injustices perpetrated by the US Government against its people can be overturned. But it takes time, blood and persistence. Thinking one man could change it and all you had to do is vote is ignorance and indifference to the sacrifices made by previous generations to defend their rights.