I don't think the design of the shuttle is stupid at all. They took technology of the time and made something that worked and worked quite well. And, they've been improving on it over time. One of the reasons that there are so many different types of tile is that there are various needs - there is no single type of ceramic tile that meets all needs concurrently.
No, I think the shuttle is a long series of problems that were overcome, sometimes ingeniously, sometimes brutally, sometimes with math, and sometimes with simple commmon sense. The ship was a series of works, not a single contiguous design. Because that's how new things are developed.
The next models will be better than the last. 7 people have lost their lives in a risky business - it is the nature of NASA to learn from this and improve the program. In the scientific sense, this may be a quantum leap. In the human sense, it is a tragedy.
Make that 14, 7 each on Challenger and now Columbia. It's really too bad Enterprise was not made in such a way as to be upgradeable to space worthyness, but as I understand it, it wasn't. (In case someone doesn't know, Enterprise was the first shuttle, but it was only used for "drop tests", from the back of the same 747 they use to transport the shuttles back to Kennedy if they have to land elsewhere, usually Edwards. They did this with pilots in Enterprise, flying it back to the dry lake at Edwards.)