For the record; I am a "box keeper".
Some people may be more inclined to buy from me if they see that all the bits and bobs have also been looked after (as well as the lens, camera, whatever). So I may achieve a sale to someone when pitted against someone else advertising without the box, etc. - great
If it makes no difference to some, that's fine too.
Think about it; I suggest it is very unlikely to put someone off buying, is it - so where's the harm?
If others wish to recycle, as do I with almost everything I can (that I have no future use for), that's fine.
Live and let live, Dave