The problem with that is that people aren't asking for AI generated images in the style of Raven from Topeka with an Etsy shop. They're asking for Ghibli. So the people whose livelihoods are most directly impacted are (assuming they're not centuries dead) the famous, talented, and trend-making artists, not the lower tier making bad Precious Moments knockoffs. Society's problem is understanding that not wanting to pay for bad Precious Moments knockoffs is rational, while not wanting to pay, say, a Studio Ghibli for quality, professional creativity is insane.
Except they didn’t do any work for the exposure. If a marketing agency had come up and executed the Ghiblify everything model as a PR stunt we would call it the most genius creative campaign of the decade
They did though. The studio engaged in tremendous amounts of work and created good will, in addition to their specific creative works. Their visual style is tied up in that good will. Use of the visual style for profit without consent is, at least ethically, misappropriation of another's value. And "You should be pleased I used your creative work because now more people will know about you and you will make a lot of money from this!" is one of the oldest defenses to misappropriation of creativity.
I'm not even mad. We do a terrible job in our society of valuing artists and creative people generally and in explaining the value of intangible things, especially something like good will. People have been misappropriating fonts and clipart and screenshots in presentations and posters and whatnot, duplicating clever branding ideas and the creative efforts of others, and so on for _decades_ if not longer, all without ill intent. It's something we need to fix and never will. But when that becomes a channel for another to directly profit, it begins to venture out of harmlessness.
As if the Ghibli trend wasnt just a short trend people will have forgotten about in 4 weeks... Also I couldnt care less about big studios, they print money anyway.