SLS exists because of parts of the politicial landscape that aren't changing anytime soon. There was no industry based on X-33 or X-38, but the people behind Freedom got ISS, and now that's going they get the SLS core stage. The shuttle workforce gets CXP, and the CXP workforce gets SLS. As far as we can tell SLS is doable with flat budget, so it'll probably reach the flight article point, but if it does it's immaterial. The rocket is a side effect. No program for that has got past the council of ministers. Crewed flight doesn't fit in with the ESA ethos.