The compromises arising from NRO and other intel/military requirements may very well have "sunk" the Shuttle (or helped do so); if so, it was only after the same compromises likely helped it garner much of the political support necessary to build it in the first place. DOD caused all sorts of headaches, but the alternative probably would have been no launch system rather than a better one. It certainly helped protect the program when it at risk:

> When in 1979 President Jimmy Carter considered canceling the shuttle program because of its cost overruns, it was the national security uses of the shuttle, particularly in terms of launching the photo-reconnaissance satellites needed to verify arms control agreements, that convinced the presi- dent to continue the program. Once the Reagan administration took office in 1981, an early action was to confirm as national policy that the shuttle would be “the primary space launch system for both United States military and civilian government missions" (Logsdon, 291).

Maybe we'd have been better off had that happened, then or earlier. But there's little indication that NASA would have been able to successfully get approval for a less radical vehicle without the Shuttle's biggest selling point at the beginning: cheap, reusable, with a fast turnaround time. And in terms of mission capability, everything and the kitchen sink to boot.

As for the compromises, among other examples, in 1969 the Shuttle's payload bay was "...in fact sized to launch HEXAGON," or Keyhole-9, then in development, ten feet in diameter by 60 feet long and over 30,000 pounds (Logsdon, 167). Well and good, except for the fact that HEXAGON would be EOL when the Shuttle started flying and thus was never expected to be launched on it. But they figured any future satellites would be the same size and weight, so the Shuttle was likely designed around those parameters as a result. Oops.

For what it's worth, even if the national security community hadn't originally pushed for the cross-range single pass capability that helped lead to the delta wing design, it's likely that NASA would have wound up there anyhow:

> The need for high cross-range was throughout the shuttle debate a point of contention between NASA and the national security community. In reality, requirements for national security missions requiring high cross-range were never formalized and more or less evaporated during the 1970s. Well before that time, however, NASA had decided that a shuttle having significant maneuvering capability as it returned from orbit was needed to survive the heat of entry into the atmosphere. So while the national security cross-range requirement initially drove NASA to a particular shuttle orbiter design, one with delta-shaped wings and the thermal protection needed to resist high temperatures during a maneuvering entry, NASA likely would have adopted a similar design even if that requirement had not been levied in 1969. Whether NASA would have gone forward with a shuttle having a 15 × 60 foot payload bay and powerful enough to launch the most heavy national security payloads is not as clear; in the final days of the shuttle debate in December 1971, NASA put forward a somewhat smaller and less powerful shuttle as its proposed design (169).

I cannot recommend John Logsdon's After Apollo? Richard Nixon and the American Space Program[0] enough. It's a fascinating look into the politics and challenges NASA faced even in the heady days after Apollo 11. And, yes, the mistakes: by DOD, NASA, congress, and the White House starting with Nixon.

0. https://www.amazon.com/After-Apollo-American-Palgrave-Techno...