Not at all. They were explorers and heroes. They readily accepted the risks. I hold them all (all astronauts) in high esteem and am in awe of their enthusiam for manned exploration of space. It's a dangerous profession.
But suggesting we all cover our heads and end manned space flights (or never should have started) because there is a risk involved is plain stupid. America wasn't built on that spirit and these brave souls of Columbia, if they could speak to us, would unanimously disagree with your thinking.
Not only did they accept the risks, but they knew the risks better than any of us here (unless there are some astronaut lurkers out there). I echo your sentiments with fervor.