I voted for dispensing with the system completely. But, failing that, I'd say down-voting should require some sort of accompanying explanation.
Now, I have, on occasion, used voting to anonymously endorse a comment someone has posted; a thought or concept that I could support which I felt needed no additional input from myself. In fact, I've used it once, just now, within this very thread.
However, I don't believe I've ever down-voted anyone, for any reason whatsoever.
If I disagree with something that someone has posted, and I feel it warrants a response, I'm naturally predisposed to taking a moment to offer my contrary view on the subject, rather than simply clicking a mouse to down-vote. That mouse-click offers no explanations, insight, alternatives or offer of dialogue regarding the reasons behind someone's disapproval. I guess that simply doesn't work for me.
Maybe employing a separate reputation and post-approval system would be a step up, although I doubt I'd be inclined to use it any differently than I do now. Short of some very personal attack, I don't see myself clobbering the reputation of someone I know only through a handful of their words. (Especially if English possibly isn't their native language.)
Do we need to indulge in the vanity of a beauty pageant or popularity contest? Personally, I'd say no. While we may disagree with certain people on this or that, aren't we already on notice as members of these Forums to never confuse disagreement with disrespect? Further, how does someone, independent of their opinions regarding game-related topics, get to evolve, reputation-wise, into "bad apple" territory and still get to hang around?