Wikipedia says "shortly before Polyus' launch, Mikhail Gorbachev visited the Baikonur Cosmodrome and expressly forbade the in-orbit testing of its capabilities." It wasn't the case that USSR upper power hid its cruel intentions or that space industry was more militaristic than Politburo.

Buran had other interesting features, like non-toxic propellants and longer ability to stay on orbit. It's not that Soviets always learned from their mistakes and made better systems - sometimes they couldn't, and sometimes the problems were internal to the system, like grounding of TKS after Chelomey's death - it's that sometimes this approach did lead to improved results. Soviet engineers were quite capable in aerospace.

Regarding economics of Tu-144 flights. I've heard that economics of civil aviation in USSR was rather weird - political pressure dictated having civil aviation, economical realities dictated subsidizing most - not only Tu-144 - flights to keep them affordable, yet this approach also had side benefits in keeping industry, which essentially was tailored for military orders, occupied with projects, testing, maintenance, learning, education of specialists, even international sales.

Correct. Add to this that in the USSR civil and military uses were much closer related than in the west, for an example, see my previous comment: the engine of the Tu-160 bomber was later fitted to the experimental Tu-144LL. see https://en.wikipedia.org/wiki/Kuznetsov_NK-32

I am not quite convinced about the test limitations for the Polyus station; I mean according to Anton Chechov, that (laser) gun in the picture would have to shoot, at some point. Maybe that would have resulted in much earlier conflict between the political leadership and the military industrial complex, who knows. They mentioned that that they had the Buran launcher fuelled up and ready for launch, while attempts were ongoing to push the decission for the test launch through, I mean that sounds like of lots of politics was going on behind the scene, assuming that this exercise would have a significant risk and cost a non trivial amount of money.