Although the murderer was a great example, I don't think you saw the light. You say you have over 36 000 members and you find your IDs to be at 42 000. Well, say I was a member with ID 47 015, and I killed my subscription to your service. I decide that I want to have my old account back, but since my account ID has already been taken, I cannot.
It also raises many other logical problems, you would have to rewrite any other table entries that link a user to a thread (for a forum example) and that could certainly become tedious. ALso, for archiving ans statistical reasons, this is defnitely not useful, as many records would be re-written due to the use of this system.
I was once like you, and couldn't stand the missing IDs, but in time, you learn to get over it. It's just an ID, who cares if they don't follow perfectly in order, you are probably the only person who knows and even cares.
