I agree with you mostly, but I think you're slightly missing the point in this bit. Suppose you had searched for "eggplant tofurduken recipe" and the result that Aunt Millie +1'd happened to be shown - would you appreciate knowing that she had looked at the same page and approved it? I know I would.
I think people are reading a bit too much into this as if it's now going to have a huge influence on Google's search results, taking precedence over the actual search terms. I think it's actually going to be far more incremental than that.