Re: Holland was clearly making a point..
Those users who need reply all should have the clear option of choosing it, or setting it as default. For the reset of the world, 'reply all' should default to BCC, and the target should reset to equal the sender. So that people who have mail set to hide any not-directly-addressed email don't even see it.
And that should be the case whenever the 'reply all' list is longer than zero. Because that will make the behavior consistent, which will be helpful for people who don't really need to reply to everybody using open addressing, and also helpful for people who need to remember to choose the correct option when deliberately replying with open addressing.