Voting is a very important part of a healthy community, and I think people should be encouraged to vote as much as possible. This point was raised on Math Stack Exchange, and much of what was said there may also apply to chess.SE:
Every Stack Exchange site will eventually end up with a different "base level" of voting --- that is, the expected number of upvotes for a question of a given level of excellence. (This effect occurs because people see a good question, but already with a certain number of votes, and think "oh, I would have upvoted this, but it already has enough".)
It's easy for us to affect this "base level" by encouraging high levels of upvoting now. We're setting the standards, and this really will have an effect.
In case it's not obvious: the rationale for wanting this base level to be high is that it provides better positive feedback to good contributors."