Although the voting system is open to abuse of all sorts and there are many potential things wrong with it, like PerlMonks in as a whole it generally works very well in practise.

Actually human nature mitigates some of the problem you raise in any case. Interest in the site is sustained by nodes and replies, not by the voting system. People who are too lazy to read node contents are generally too lazy to bother voting - the attractiveness of gaining XP is not, or at least generally should not be, a sufficiently large motivator that most people will simply go out and down vote the first n nodes they encounter (although I suspect there are a few that do). In any case that is a very slow and labourious way of gaining XP - one good reply will garner many more XP in a day than spending all your votes.

The voting system is a way of signalling to posters agreement or disagreement for a point of view or, more commonally, as a reflection of the perceived quality of a post. And actually the system works so well in its own subtle way that I often find myself wanting to upvote material people have submitted to other sites I visit.

I know that not everyone is the same and I am sure you are right that some people just pull out their big black pen and put ticks and crosses beside the first nodes they happen on until their votes are all used. However, for myself, when I read a node I strongly agree or disagree with I vote. When I read a well written node, I vote. When I read a poorly written or badly formatted node where the OP clearly hasn't bothered to at least skim the site material describing how to format node material, occasionaly I downvote. In each case I vote after reading a node. Very often I read through a thread and vote on pretty much everything. Sometimes I don't read a thread at all until until it gets a reply from one of the many monks I respect. But in all cases voting is very much a secondary activity compared with reading and evaluating the posts - that after all is what the site is really about! Despite being fairly active here, many days I don't spend all my votes and it is very seldom indeed that I wish for more than I have available.

"You can lead a horse to water, but you can't make it drink." - the voting system gently leads, but the real reward is in the drinking.