Personally, I'm not surprised when I don't see the numbers 0 - 4 crop up that often if at all because I generally can't think of many games that would score that low. I've been reviewing for three years and there's only been two occasions where I scored something under five, which is below average for me.
Several months back I would have agreed with this, but I've played a couple of games since then where I couldn't think of anything negative to say so they got a ten by default. If you can't think of anything bad to say what are you supposed to do?