I'm going to throw this answer out there at my own peril: We don't have very many votes due to pure and unabashed Laziness.
There are plenty of good (and bad) questions here on D.A. It's not that hard to determine whether or not a question is helpful, needs a solution or is relevant to the Drupal community. If the question is beneficial to the reader or even made them think differently about a topic, then the reader should upvote it. Likewise, it's also not that hard to see that a question is poorly formatted, is unclear, or is a duplicate of another. If it falls into one of those categories, then hopefully an edit can help, otherwise downvote the question. That being said, I'm not sure if a checklist would help. I think we simply need to encourage users to vote.
Perhaps there needs to be some sort of initiative to raise awareness on voting as a core SE concept. Maybe there should be a sitewide announcement about how important it is to vote, and/or draw attention to the badges that reward voters.