How is this different from a FB Like or a Retweet button on a blog? Or do those rub you the wrong way as well? Not trying to be snarky; I'm genuinely curious.
I, personally, am fine with those when they come after the article. However, asking me to like, upvote, retweet, subscribe to your RSS feed, or do anything indicating that I like an article before I have read it is a really, really good way to get me to close the tab and go read something else. Even more so if, as on some sites, the request appears in a pop-up thing which obscures the text of the article.
FWIW, I don't like those either. I think it adds unnecessary clutter to the web.
And: Lowering the threshold of work needed to share something reduces the average value of the things shared. It's not a big deal when you can moderate who is sharing things with you, but it's catastrophic for a communal service like HN. It is the path to funny cat pictures.
I think there's an element of game theory here though: the people putting out the HN equivalent of funny cat pictures (like angelgate or other drama) are going to self-promote, and heavily. If they weren't the type to do so, they wouldn't write content like that. So the defense should be two-fold: encourage the HN userbase to only vote up good stuff, and create good content yourself and promote it. If you don't promote your own content, it'll be overshadowed by the funny cat picture people who do. Ideally, no one would self-promote, but if the guy with crappy content does, the people who write good content should too.
Of course, this supposes that I'm not in the category of people creating funny cat picture content. And the realization that perhaps I am more than I'd like is somewhat uncomfortable. How do you know for sure?
Oh, sure. The question is how best to get those readers.
I'm one of those who do not respond well to blatant prodding for mindless promotion. I've some bookmarklets for posting things on friendfeed and HN, and use them when a site is interesting.
Maybe those buttons work well with others. But will they create the kind of audience you want? Does that even matter when you're just trying to get some initial attention?