I log all dives (but not pool) but for a different reason from what I have seen so far: Just in case I, or worse yet someone else, need to give information about my dives to the doctor.
This months (Feb 02) DAN Alert Diver magazine has a story of a woman with cerbral DCI. Her symptoms included feeling fuzzy and could not remember things. She of course never logged anything, or use dive tables or a computer.
Just in case I should be in a medical difficulty, and unable to speak for myself (DCI sysptoms can include paralysis) or am fuzzy on my memory, my dive log will be there to give them some idea of when, where, how deep, how long, how often and with whom I was diving. That could be important to my medical treatment.
Of course, maybe someday Iwill want to go for some other certification, I will have them logged.
Just my 2 cents.