I'm trying to understand what you need.
Currently, the way it works is, you vote a topic down and it collapses. It does not completely disappear because you may find later that you want to open it up again. A complete disappearance would prevent that. Hence I think the current system fulfills both of your needs: (1) the need to knock away things that don't interest you but also (2) make it possible to retrieve them in the event that you change your mind at some later date. Perhaps I'm misunderstanding your observation.
As for the other comment, re
forum single-mindedness, certainly that's your opinion but anyone who does not sort by "Most Votes" and/or who shows "All Time" will see every single topic on the site, although they may have to page in order to find things. But that's the way it was before -- it's impossible to keep every single topic on the site on the first page as the business and tiny print needed would make the site virtually unusable. Really, the main thing that voting does is allow for more customized sorting, rather than forcing the user to accept only one means of sorting. In fact, in the older version of the site, you were essentially beholden to whatever people foound interesting as those were the topics that were bumped. Other things were buried quickly if the site was very busy. Here, you can re-sort in a manner that differs from the majority.