> These are people who are very likely at the top of their fields, have gone through rigorous (and costly) training, and are going up to do very specific jobs

That is irrelevant to the level safety precautions. Unless you were trying to argue that their costly training makes them worth more than other people. I hope that is not what you were arguing.

> doesn't mean we shouldn't be doing everything we can to ensure a safe flight

At some point you have to declare something 'safe enough' since 100% safety is an impossible perfection. Bicycles aren't 100% safe, but we don't go around insisting on multiple backup systems. Personally I do find it curious that the standard of safety for astronauts is so high. The cynic in me suggests its less out of concern for the astronauts and more to do with the publicity fallout that occurs after disasters and the damage to other assets. The optimist suggests its more a concern for all the ground crew and spectators who are also at risk. There is potential for a lot more than 4 casualties when you play with that much fire.