Well the light went out on its own and hasn't returned yet.
Since it is my 20 year old daughter, and car is in my name (even if it is hers) and while she is in school I have committed to maintaining it, I do feel obligated to get it resolved especially having been involved in product safety underwriting I know that safety is viewed as an entire system and when items supplement each other compromises are often allowed on the individual systems which would never be tolerated if there was one single safety critical system.
Having said that, if I were driving the car, I would not worry about it. It is my choice and like adsm08 says it is supplemental.
As far statistics, I don't think anyone can really know what effect airbags have. There has been so much done as far as structure and such. Culturally seat belts have become more taken as a given and is far more standard habit now then in the past not to mention seat belt laws in some places.
And if you want to argue but they save lives when seatbelts aren't used, well that proves nothing as far as them with seat belts on.
I also look back at why airbags were added. They were brought in as a passive restraint system to solve the problem of people not using seat belts. Then when airbags killed some people, they insisted that you have to have your seatbelt on with them. And maybe the combination is better but I don't know how in the world anyone can isolate the effect airbags have in the overall safety improvement given all the things changed at the same time.