That type of room i not just a safe, but also a "panic room." Which could be anything from living in a terrible area and worried about civil unrest, to someone wanting a 100% confidence their tornado shelter would protect them no matter what.
In our case the panic room was definitely more weather related than burglary concerns. During the course of living in that location (I am in a different state now, but was there for 12 years in that house) we had 5 major weather incidents that were declared disasters by the state, and once nationally. We never had a single home invader, trespasser, burglar, or otherwise. The safe was more about fire risk than theft risk, but if you're going to do it you might as well go all the way. It was TL-30 rated but also rated for 4 hours at 2500F. Same thing with the safe room, if you're going to build it, might as well protect against everything.
