A good friend of mine was actually considering becoming one of the US distributors for Hit-Air, who makes the air bag jackets. In concept, it seems like a great idea, but after looking at the specifications and how it's triggered, I wasn't wild about it. It's triggered by a tether between the jacket and the bike. If that tether is broken, the jacket inflates.
As a sportbike rider, I move around on the bike quite a lot, and could only imagine the result when I slid my butt off the seat, dropped my shoulder, and then POOF! my jacket inflates because the tether was stressed the wrong way.
I've had cruiser-rider buddies tell me that their fear would be getting off the bike at a fuel stop, forgetting the tether, and having it go off. While the latter would be far more amusing and inconvenient than painful, I would think, neither of them is a desirable result.
So even if they may be safe in an accident, I don't think they're going to see marketing success here because of those considerations.