Comparing the figures of Polls/Survivors to other sub forums is an apples to oranges comparison, it's an inflated figure. There's a higher turnover of threads because running one survivor involves a thread per round which is every day or two before the poll closes and then it's finished (or however long it is). In any other sub-forum, a discussion like that is all in one thread, so that's not an accurate comparison.
Then compare the posts to threads ratio for every sub-forum. In the polls sub, it's an average of about 10 posts per thread, while in every other major subforum, that ratio is 100. A lot of threads, with a lot less activity, for the reason already mentioned. The average number of votes isn't much higher than the post count, with maybe a dozen votes on average.
I remember it exists, I just don't see the point of it. Personally, I'd ditch both reviews and polls/survivors altogether. Oh, and finally get rid of events while you're at it.
Now that I think about it, even just removing the reviews and events subs would technically move polls/survivors up by two places, so that would be a win-win! It moves up, without having to actually move it up!