I think the main cause of increased down-votes is due to the increasingly absurd questions that get asked on this site, however I believe that a down-vote is not enough to disprove/disagree of/with a question or an answer, each down-vote should ideally be followed up with some constructive feedback, perhaps we can include a new feature that does not cause a down-vote to be registered unless a comment is included, of course there must be a way in which the user is notified of this when they attempt to down-vote, this will help and change the attitude of members of the community and cause them to think twice and review their motive for the down-vote in the first place.
One thing that I realised as well, there are users which join the community, ask a single question and never visit the site again, some really good answers remained unmarked because of this.