I agree. I would even take it a step further, by applying the "1 per game" rule to the voting process as well. Or at the very least, keep the amount of tracks per game to a limited amount. It would make things a little bit more interesting and more in the spirit of 'broadening your horizon', as most voters will just list a few (of their favourite) games in their lists. Even though I still expect the major franchises to come out on top, enforcing this limit will make the outcome less skewed in favour of these games.
Sixfortyfive: I know it's a hassle, but could you update the OP with the nominations, or list the current nominations at your website? This topic will only grow as time goes on, and new voters might not know which games are not nominated yet, and are likely to nominate some tracks which have already been mentioned in the topic.