Removing the vote count was a step back. You end up with highly positioned comments that are factually wrong and no way to weigh the corrections made in replies. If you saw that a comment had 20 votes, but a reply had 500, you'd have something to go by. If nothing else, they could show the relative score of a reply to its parent.
Vote counts were struck because they were causing fights.
Paul Graham decided to risk sacrificing a little bit of comprehensibility in exchange for some extra civility. I think the tradeoff has worked very well --- especially because incivility crowds out comprehensibility anyways, so that almost anything you do to make a thread more civil will have the knock-on benefit of making it easier to read.