To extend the analogy, imagine the circle as a probability distribution; for simplicity, imagine it's a bivariate normal joint distribution (aka. Gaussian in 3D) + some noise, and you're above it and looking down.
When you're commissioning an artist to make you some art, you're basically sampling from the entire distribution. Stuff in the middle is, as you say, easiest to reach, so that's what you'll most likely get. Generative models let more people do art, meaning there's more sampling happening, so the stuff further from the centre will be visited more often, too.
However, AI tools also make another thing easier: moving and narrowing the sampling area. Much like with a very good human artist, you can find some work that's "out there", and ask for variations of it. However, there are only so many good artists to go around. AI making this process much easier and more accessible means more exploration of the circle's edges will happen. Not just "more like this weird thing", but also combinations of 2, 3, 4, N distinct weird things. So in a way, I feel that AI tools will surface creative art disproportionally more than it'll boost the common case.
Well, except for the fly in the ointment that's the advertising industry (aka. the cancer on modern society). Unfortunately, by far most of the creative output of humanity today is done for advertising purposes, and that goal favors the common, as it maximizes the audience (and is least off-putting). Deluge of AI slop is unavoidable, because slop is how the digital world makes money, and generative AI models make it cheaper than generative protein models that did it so far. Don't blame AI research for that, blame advertising.
I like the picture, but I'd be more impressed with the exploration argument if we were collectively actually doing a good job giving recognition to original and substantial works that already exist. It'd be of greater service in that regard to create a high-quality artificial stand-in for that limited-quantity "attention" and "engagement" all the bloodsuckers seem so keen on harvesting.
(And I do blame the advertisers, but frankly anyone handing them new amplifiers, with entirely predictable consequences, is also not blameless.)
I read this argument/analogy and the "AI slop will win" idea reminds me of the idea that "fake news will win".
That is based on perception that it is easier than ever to create fake content, but fails to account for the fact that creating real content (for example, simply taking a video) is even much easier. So while there is more fake content, there is also lot more real content, and so manipulation of reality (for example, denying a genocide) is much harder today than ever.
Anyway, "the AI slop will win" is based on a similar misconception, that total creative output will not increase. But like with fake news, it probably will not be the case, and so the actual amount of good art will increase, too.
I think we are OK as long as normal humans prefer to create real news rather than fake news, and create innovative art rather than cliched art.
A small technical point:
Tastes are almost never normally distributed along a spectrum, but multi-modal. So the more dimensions you explore in, the more you end up with “islands of taste” on the surface of a hyper sphere and nothing like the normal distribution at all. This phenomenon is deeply tied to why “design by committee” (eg, in movies) always makes financial estimates happy but flops with audiences — there is almost no customer for average anything.
I agree with your conclusion.