That lowest-accepted quality also declines over time, as generations after generations of people become used to rock-bottom quality. In the end, there's only slop and AI will make the cheapest slop ever. Welcome to a brave new world. We don't even need people anymore. They're too expensive.
It's not inevitable that it's a race to the cheapest and shittest. That's just one (fairly strong) commercial force amongst many.
But you're talking about PAID artwork, and yes: when it comes to paid art, money does matter.
You can't expect artists to completely ignore financial incentives, and at the same time expect the creative industry to just throw lots of money at these artists. That's just not how (capitalist) businesses work.
The world absolutely does care for super high quality artwork. But very few people are willing to pay $2000 for a movie ticket when they could also go to 100 $20 movies.
On top of that: who gets to decide what is high quality, anyway? The creative world is fraught with corruption, elitism and "who knows who", making it very unlikely that a highly talented artist is ever even "discovered".
It's a lot more complicated then just "money is all that matters".
And finally: I don't think this "trend" is just in the western world. Show me a place in the world where artists are rewarded based on purely the quality of their work, rather than the profitability of their work.
I bet that a good animator could make a really impressive 4-second scene if they were given a month, instead of a year. Possibly even if they were given a day.
So if we assume that there is not a binary "cheap animation vs masterpiece" but rather a sort of spectrum between the two, then the question is: at what point do enough people stop seeing the difference, that it makes economic sense to stay at that level, if the goal is to create as much high-quality content as possible?