Maybe I missed it, but when the cars 'shut off' was the ignition switch just going to the off position or to the lock position?
If it were going to lock then that is really bad and I can understand all the crashes. If it was just killing the motor I partly blame the motorist for not paying attention and not knowing how to handle a basic emergency situation. Regardless, not a good situation, GM definitely hasn't handled it like they should have.
I bought my daughter a new 2006 Cobalt and the other day I tested it out and is what happens is the power steering assist goes and power brakes go (no steering lock). So I explained to my daughter if she does by chance bump key and turn it off to simply use a little more arm and leg strength. I read the teens that died in one of the accidents listed were not wearing seatbelts but GM took the rap because the airbag did not deploy.