Minimizing payload at any point was easily worth a billion dollars. And given how heavy and nessisary the radiators are (look them up), you can bet a decent bit of research was invested in making them lightweight.

Heck, one bit of research that lasted the entire lifetime of the shuttle was improving the radiative heat system [1]. Multiple contractors and agencies invested a huge amount of money to make that system better.

Removing heat is one of the most researched problems of all space programs. They all have to do it, and every gram of reduction means big savings. Simply saying "well a DC will need more of it, therefore there must be low hanging fruit" is naive.

[1] https://llis.nasa.gov/lesson/6116

Optimization is literally how contractors working for the government got rich. Every hour they spent on research was directly billed to the government. Weight reduction being one of the most important and consistent points of research.

Heck, R&D is how some of the biggest government contractors make all their dough.

SpaceX is built on the billions in research NASA has invested over the decades. It looks like it's more innovative simply because the USG decided to nearly completely defund public spending in favor of spending money on private contractors like SpaceX. That's been happening since the 90s.