Lyric discussion by MadSc1entist 

Cover art for Disappointed lyrics by Nine Inch Nails

I think the song is more introspective than the explanation given about Obama. Trent uses several personal pronouns throughout the song and I odubt he's refering to himself in the third person as Obama. The song is about women building up a hype for reznor based of prejudement before they really get to know him and when they finally get with him it's impossible for him to fulfil the what ever the womens expection that she had of him.

The verse look at you superman with all the world to save you'd think by now you'd figure out that nothing's going to change

Is about someone trying to change or fix reznor, but what did they expect? After all these years did you actually think he would change, then they are disappointed.