In spite of some snark, I still find HN to be a pretty good community. Up and down voting actually reflects this. On most sites, it is, as you pointed out, a way of keeping score (you know how it goes, if you like Mitt Romney, you vote up, if you like Obama, you vote down, regardless of the tone or content of the post). I actually feel that HN is still unusually inclined to actually use the voting to moderate rather than keep a tally relative to pretty much anything else out there.
I'd be really bummed to see this go.