Another argument for the electoral college. In our current system, 400K votes from New York don't matter because it's clear who won the state, and even if they all go to Romney it won't change the electoral map. But imagine a popular vote system, where 400K votes from any state could alter the outcome of a close election. Luckily, with the way things are now, outstanding ballots will only affect an election if they come from a very close state that acts as a tipping point in the electoral college totals, so the chances of a hung election are slimmer.
There are lots of systems you can come up with that might avoid problems with some other system. For example, a national popular vote system would have avoided the recounts and legal battles that took place in Florida in 2000.
