When did wearing a tie become a marker of elitism? Time was, Americans wore ties to go to sports events. Although dressing neatly is obviously a thing of the past -- as any trip through an airport makes manifestly clear -- doing it is actually a sign of respect for oneself and for others.
And in fairness, given his efforts to overcome invidious stereotypes and rise to power as a young, African American politician (an effort incalculably damaged both by Rev. Wright and his wife), it's probably true that Barack had to work twice as hard to make sure he sent a message that he was an upwardly mobile, professional-type guy.
Williams confuses outfits with attitude. One didn't see Ronald Reagan running around in jeans and a tee shirt except on his ranch; he wore a coat and tie to campaign, and no one ever thought of him as elitist. Elitism has to do with one's attitude toward and understanding of the lives of regular people -- not with one's willingness to imitate them.
Strikes me that wearing a tie is the least of Barack's problems. Oh, and by the way, can you imagine the feminist outcry it would elicit if Williams had asked Hillary Clinton why she wears pants all the time?