I have to say I prefer the system the way it is. I appreciate the sentiment for giving a post more votes (ie. more approval or disapproval), but the way it stands now a vote should be a more considered opinion.

When the voter gets only one chance to vote then the voter presumbably puts a certain amount of thought into what they vote for. If you care about voting then you won't waste your votes. And posts voted up will likely be more worth reading.

Perhaps that is the reason the system was set up the way it is.