Потому что мне было 22 года!
Really, that was the largest part of it -- I was fresh out of college and "full of myself" (arrogant).
But if you want me to be more specific: At first I was shocked by the lack of "customer service" skills -- is it so difficult to smile, продавщица? And I was shocked by the dirt and graffiti in the apartment buildings -- why didn't someone take the initiative to clean them (my parents were in the military, and I was a Boy Scout)?
And I was REALLY shocked by some of the racism and antisemitism that I heard from seemingly educated Russians. (The homophobia, I was prepared for... but not the rude comments about blacks and Jews!)
But later, as a young adult with no money living in New York City, I began to understand that all of this existed in America, too. Communism may have made some of the problems worse in Russia -- people who don't own the property they live on have less incentive to take care of it, for example -- but mostly, it was human nature.
P.S. I'd be grateful if someone could suggest colloquial Russian equivalents for the blue phrases...