They drove the best Apollo engineers to leave NASA shaking the head in disbelief and left a generation of engineers in charge of human spaceflight who couldn't tell the difference between reality and fantasy. Who actually believed routine spaceflight was possible and easy.

Before Shuttle NASA was seen as a role model of how a government engineering agency should work. Afterward it became national joke which is why no one believes they will be able to return to the moon, let alone go to Mars.

Change starts with facing reality and the reality is that Shuttle and ISS were the wrong programs, at the wrong time, done for the wrong reasons. Until NASA, and Shuttle/ISS supporters accept that there is no hope for the future, at least a future NASA will be part of.

Thanks to Shuttle/ISS the space program is still stuck in 1976 without the advantage of a generation of Apollo experienced engineers running it. NASA went from boldly going were no one has gone before to wearing a rut in LEO.

A good starting point for the rebuilding would be to purge the agency of engineers who still believe in the fantasy of routine spaceflight.

The only lessons from Shuttle/ISS is that spaceflight is not routine, its not easy and you don't what to be entangled in international agreements - something the Apollo generation of engineers attempted to tell NASA.

A generation of engineers wasted is a terrible thing and that is the real legacy of Shuttle/ISS. A generation lost.