While I welcome anyone to disagree, it is completely plausible to me that scenarios involving a "culture of down-voters" could become a negative burden on the site, and actually discourage potential contributers of positive and/or useful answers to questions. To me, that would not be a good thing.
Overall, I think the SE does a pretty good job of having rules and intentions surrounding down-votes, and outlining these. For example, deducting reputation points from those who down-vote, often can make users weigh their reasons for down-voting more seriously. There are rules regulating serial down-voting in place to prevent such disingenuous actions. I think these rules have clear intentions, in that they are meant to discourage actions that are negative to the site, while at the same time leaving the down-vote in play for the well thought out voter for such things as limiting posts, and responses that are detrimental to the quality of the site.
However, albeit subjectively speaking, I am not lately feeling sufficiently impressed with the voting trends, compared to when I first joined, based on how I see votes assigned to a variety of posts. I also see a number of posts reflecting the dissatisfaction of people who have been down-voted. Of course, that does not mean the down-votes were not for good reasons each case (in many cases they are), nor that my subjective senses are objectively coherent. Never-the-less I raise the question, objectively-- When does down-voting actually harm the site's culture, despite the voting guidelines, and how could such be assessed? How are/ and are voting guidelines occasionally reviewed/ modified to keep things "pleasant" so to speak?