https://en.wikipedia.org/wiki/Yutaka_Nakamura
Is one who comes to mind. It requires a specialist and costs an outsized amount of money per frame compared to regular scenes. In western live action films it requires a director who intentionally wants to emulate that style and a studio that is willing to spend the money to do so. The incentives probably aren't aligned for big blockbusters to have well-choreographed fight scenes anymore.
There is obviously still an appetite for well choreographed fight scenes, but they are in the new Western feature-length animation projects (Spiderverse, Puss in Boots), probably because this generation of directors and animators grew up watching Yutaka Nakamura's fight scenes or RWBY.
But IMO asking why so much new media has bad fight scenes is like asking why so much new media has poor writing. It's a commodity that people probably didn't care about that much.