NASA is a pork barrel project and isn't about space anymore. It was appropriate for the era of getting to the moon and should now get out of the space game and be replaced with separate organizations for supervision and mission funding of private contractors as has already begun. Going to the moon was actually about shifting the high cost of rocket development as well as putting a pretty face on large rocket tests. It was a PR thing. The defense department got their rocket tech which they were going to get one way or another but the public for it's money got modern satellite telecommunications and boosted electronics developments.
NASA over designs things with the greatest chance to work the first time but it takes longer and costs more. The economical way of design is to launch and use cheaper prototypes in the field and to actually want things to explode a good portion of the time. With every failure you improve the design and know what to look out for. It's simply too expensive and slow to try to anticipate everything. Better to be judicious and do your best and then learn as you go. Better to build ten rockets for the price of one and expect at least 7 to fail in the first batch. You ultimately succeed and do more for the same money.