I concede that it would be very cumbersome to search or sort dives based on criteria such as depth, temperature, etc. with a paper log - actually a word processing document in my case. But I've never had any reason or desire to sort through my dives that way. Just sort of knowing what number, where, when, with whom and what I thought about a particular dive are all I really care to document.
As an added bonus, it is really easy to document dives for the rest of the family. I end up doing log books for the wife and kids too. It is very easy to cut and paste each dive that they do into their individual logbook (actually just a word file) and keep their tallies for them. I don't think I could easily do that using any of the commercial software. It would probably mean documenting each dive 4 times if I am with both kids and the boss. I like to keep a running count for us all: me #342, boss #101, 16 year old daughter # 136, 15 year old son # 80.