Your disgust is exactly my point. They have thousands of years of history but none of that matters because they've failed to build enough toilets the past few decades.
sad reality is that a huge% of people don't actually care about the music or movies themselves, they care what they're associated with. 自有大儒为我辩经 and all.
if South Korea or Japan were politically and militarily independent from the US with no other changes in media quality or output, their soft power would ironically
decrease, as they'd no longer be palatable forms of American power for Asians, but just some random countries that sell shit to the world. They don't have to be actively suppressed for this to happen. A significant portion of people only consume media for the association with power. They don't care about the quality music or the movies at all. It is like how there are people who don't actually like a type of food, gritting their teeth and forcing themselves to say it tastes good, even as they're obviously struggling to not spit it out, simply because it is from a 'high class' culture.
Look at Vietnamese pop culture as an example. The Vietnamese song 叹 went viral in China last year and brought attention to V-pop. I think that V-pop has significant potential and is objectively quite good. However, I think that only in Vietnam itself and neutral markets like parts of China and ASEAN could V-pop become popular. I don't think even the Vietnamese diaspora listen to it.
Vietnam is independent from the US and relatively poor. So even without suppression people don't want to listen to music that they perceive is from a poor or weak country.