Observation on the U.S. Election Result

President-elect Obama won 52.9% of the popular vote in the recent U.S. general election.  So close to half of the voters did not vote for Obama.

It makes me wonder about the electoral process in liberal democracies.  The results are often very close.  Why is this?  To my mind one would expect that in the course of a campaign one candidate and his policies would emerge is clearly superior to that of his rivals.  I would therefore expect result to be say more than 70% in favour of one over the others.  But it rarely seems to work that way.

It makes me question how really "democratic" our election system is.  But that being said it is clearly the best system compared to all others currently existing.