Forget the greenie crap, styrofoam is in heavy use everywhere else still. Just look at all the boxed electronics and packing peanuts.
EDIT: And it was just as hard to lift a toy back then as you had to open the box, then open the sealed inner bubble, and also make sure you got the accessories, etc. With the carded toys today, just ripp open and take the insert with everything tied to it.
As for the boxed voyagers and up, they're just too large to steal.
________
Marijuana indica