I was in Tokyo over New Years a couple years ago. Along with the "Lucky Bags" is the other custom of giving kids "Lucky Money" as a New Years gift. Kids get some from most relatives. So the lucky bags get bought with lucky money. Pretty direct connection. You see mostly high school and slightly older (mostly) girls lining up very early before the stores open. We have some smaller kids so went into a toy store, a large one, five floors tall that my wife remembered being there when she was little and living in Japan. They had the bags, but they where displaying contents so no surprise. There were about four different bags and you could pick. I think a lot of the stores were letting you know more about what you'd get but it's hard to tell when you can't read the ads.
I was more interested in the many street vendors selling food. Seems they are allowed to set up on the sidewalks for new years. New Years is by far the biggest holiday in Japan.