The reason NASA's attempt at a modern launch platform has had so many problems is because they were required to base everything off shuttle systems in order to

The reason NASA's attempt at a modern launch platform has had so many problems is because they were required to base everything off shuttle systems in order to keep congress happy. The shuttle, somewhat infamously, had parts from every single state in the country - which again was done to keep congress happy. It was a giant flying barrel of pork, and so is SLS. Nothing like using fifty year old technology; the SLS is four shuttle engines bolted on to the bottom of the orbiter fuel tank, with orbiter solid rocket boosters...but because there are four engines, and the orbiter tank didn't have four engines worth of thrust under it, they've had to modify everything, and it still doesn't work properly. It doesn't help that NASA has an institutional allergy to actually developing, or even using, new technologies.