Well, the rederection link would make clear what happened to the thread. Now it's suddenly gone and as the forum layout is quite complex, it can be hard to see where it went.
I don't see how this makes the relations more complicated. Also, the extra hd space occupied is not really significant as it probably is not more than a few bytes. Of course the thread becomes dead after a short while it should be closed actually. But most threads on this forum are dead, we have thousands of threads and only a handful are still used. The redirection thread could be deleted after some time, but I don't know if there's an option for that.