[Campion]

CONGRESS mandated that the new moon program shall use repurposed STS technology, including the RS-25 engines and the solid rockets. This is not what engineers at NASA wanted to do ... they wanted to build on lessons learned and designs perfected from the Apollo/SaturnV program. This is what CONGRESS shoved down their throats.

Yes ... lawyers/politicians trying to do engineering. Isn't it wonderful? /s /s /s [ad infinitum]

The Shuttle's original use of SRBs was basically a political decision driven by [short-term] cost considerations, too ... NASA's original plan was for a (manned!) liquid-fueled booster that would fly back and land on a runway.

[NorthMountain]

a (manned!) liquid-fueled booster

I vaguely recall seeing concept art for such things ... some of it going back to the 1950s.

SpaceX is (trying to) make it a reality with Superheavy and Starship, which are supposed to be the future of the Artemis program.