Glen;
The only drawback of blowout panels that I can think of is the possibility that aerodynamic pressure could cause then to dislodge. Even so, it's not as serious as a window blowout; there are not hundreds of pieces of glass to pick up off the track. The risk to the vehicle is that the missing panel may cause instability (maybe). An explosion creates high enough peak overpressure that it should be able to hold in place during a high speed run yet be able to be blown out in an explosion. A closed container is an invitation to disaster. I remember blowing up lots of tin cans with carbide when I was a kid.
Regards, Neil Tucson, AZ