I think BL really needs to be in the same category as Scouting. If you register you get a copy.
Most boys (especially Cub Scouts) only exposure to scouting is through their home unit. BL helps the realize they are part of something much, much bigger.
We make it optional our pack. When I look at the records of who gets it and who does not, it's interesting that it's usually the most engaged scouts are the ones that get it. I know that they probably get BL because they are already excited. The don't become excited simply from reading BL. However every little bit helps.