Read thru these forums (all the threads about the encrypted logs), and you'll see that it is essential.
A lot of people change their passwords regulary and since many also archive logs, many logs are encrypted with different passwords, and this is also the reason why many people say that they can't decrypt logs anymore because they thought they were encrypted with some password, while it actually was encrypted with the other (older) one, etc...
It isn't just one of many smaller and other "options" or "features" which can be added though; it's pretty much mandatory in a batch decrypter
/ 
