hmm, somehow, user id's that don't match to the Nth member signup don't seem all that odd to me - most users never know how many'th member they are, nor do they care a whim.
Having things orderly is nice - but if you learn enough about it, you'll understand that this way, it's actually far more orderly and useful.
I personally wouldn't go _just_ as far as saying it's senseless and inefficient - no, I would even go as far as saying it's completely retarded, but that's my personal opinion, though