1. "Softer" walls have a tendency to catch a vehicle, and at 150+ mph, you really don't want that.
2. Center divider wall is a great idea for safety, and has been discussed over the years
3. I would think a catch pan would give a false sense of security, and cause a bigger problem at the top end with larger amount of fluids, fire, etc
4. An active secondary remote control,chute deployement control by teams crew chief, is not real complicated nor expensive and not likely to have too many negatives, and has merit IMO