Are you sure about the merging? I don't see what this would offer.
Yes, I'm sure. It offers less clutter. The rest of your rant doesn't make sense. Edit the old stuff into the new post, you'll have your bump and no information will be lost.
By the way, is there an official rule regarding merging new and old posts together or is this your personal suggestion as a good practice to behold?
21. Old bumps should be deleted.