What you said is a real possibility, which is why I always recommend that people wait at least one full day before "bumping" their own threads. However, know that many people will soften cour the forums themselves, and if they see a post with one reply that was made by the original poster, they will often take a look at it. Believe it or not, I have often had people jump in on threads for the first after 10 or more posts!
Also, there are instances in which your recommendation wouldn't quite work out as your envisioned. Many times, the original poster will figure out the answer themselves, and then post back saying as much. So those would be examples of threads with one reply, from the original poster himself, where the thread it actually solved (and we probably wouldn't want to show those threads among the unanswered posts).
Aside from all that, I have no idea if what you requested is even possible (the forum is a software that we use, not something that we developed, so we are limited by the capabilities it has). I know that the Board Administrators are intending to take a look at some of the Advanced Functionality at some point down the road after they get all the kinks ironed out.