This will actually change after Communities which are now in private beta. Communities disentangles visibility, downvoting and flagging. After Communities whether a post gets hidden will have more to do with the rules of a given Community and not whether the post was downvoted. In short, we agree that the current implementation is not ideal. While it is not technically censorship, it can feel like it. The implementation arose out of necessity but can be, and is being, improved.