I'm not sure if it's just me, but people seem to downvote both questions and answers more frequently here than on any other (popular) SE site like StackOverflow for example.
Is it just me or am I right? If so, what's the reason?
Here's some actual data for you.
On Gaming.SE, the average Question score is 5.54:
On SO, it's 1.57:
So we do vote a hell of a lot more here, and I'd give this as evidence that we downvote more, but also upvote more.
Gaming, as an expert topic on a Q&A site, has some extra difficulties that a lot of other topics don't have. It's very easy for sites about Gaming to devolve into trolling, flame wars, opinion pieces, rants, etc.
As such, we have developed one of the strictest communities and strictest sets of guidelines for what belongs here. We downvote things that don't belong to get the point across that no, we don't accept content like that.
Do we downvote more than other sites? I have no idea. Are we justified in downvoting bad content? Yes, absolutely.
One point that has been touched upon already is the user base/question count - sites like Stack Overflow have a larger userbase and therefore on average, more questions per minute.
Imagine that on average, votes (up or down) were 20% of views. (Grossly exaggerated)
What this means on Stack Overflow is that a single question won't remain on people's radars for very long, it quickly gets pushed out of the top 50 by other questions.
Whereas here on Arqade (or any of the smaller sites for that matter), a question might stay on the front page (or the newest questions tab) for days.
This results in more people seeing the question in general, and therefore there will be more down/up votes.