Back with an update: My son found my logbook and c-card in his backpack as we were packing to head home. I'm really happy to have it all back, and I really appreciate the great discussion here.
I can totally understand why some people don't log dives or keep a logbook. For me, though, it comes down to the fact I just like having it. I wish I would have found it in time to get it stamped at the dive center before we left, even though I understand it doesn't mean anything for my dive "career."
Just remember though, when you are 90 in a wheel chair peeing your pants, what will make your day is flipping through your dive log remembering all the great dives you had.