The SLS was never worth it. It is a program so absurdly expensive that its hard to even come to grips with the numbers.
However, in defense of the SLS 70000kg is the minimum requirement, the rocket will lift more like 80000kg.
Even now it would be cheaper to cancel it. For just the the SLS budget of the next 2 years SpaceX could easily build them the BFR. They could have three different super-heavy boosters from three different companies for the price of the SLS.
> To be fair, no one could have possibly foreseen the quantum leap in rocket technology SpaceX has made over the past 8 years since the SLS was designed.
It was foreseen. They wanted to gather proposals both from inside and outside of NASA because NASA had already realized that it might be much cheaper. They had evaluate how much SpaceX had spend on development and concluded that they would have spent about 10X more.
Non of these investigation were pushed and the SLS 'proposal' was selected. Interestingly another group inside NASA (the only other proposal) want to go back to the F-1 engine.
> But it's beginning to seem more and more like a government welfare program for Boeing rather than an effective launch system.
It was always that. Since its inception everybody called it the Senate Launch System. NASA actually did not want to build it, the Senate forced them and specifically required them to use specific tech. Its nothing but a 20+ Billion pork program.