I don't know why it isn't huge either! It may be exposure to the game? What I mean is, almost at any time of year here in Toronto, you can drive down any street, drive past any tennis court and see guys playing ball hockey.
I also think that because many people who watch NHL hockey without having played the game don't realize how hard it is to skate full speed, make a accurate rink wide pass; or what it feels like to get hit by 16 ounces of vulcanized rubber at 100+ mph.
It's going to take a little time, but I have no doubt the excitement of this game will draw new people.