The Columbia accident made us realize that we had been playing Russian roulette with the shuttle crews," Hale said.
The article.
It's indeed revealing!
Precautionary principle at work.
But is there enough sense of exploration to go further? Plenty or things were dangerous with the Shuttle. And a new spacecraft, could it be safer? The Soyuz has shown its reliability, so perhaps yes, it is possible to design a safer spacecraft.
Raoul