Not sure I know what you mean by a prevalence of fractals in art. Do you mean classical art, painting, sculpture, or other media? I think it's kinda rare. Even in mainstream modern art I wouldn't say it is prevalent, maybe I'm wrong. Are you referring to it's popularity as a digital media? Fractal can mean irregular, but I think that doesn't really cover it. I think Seirpinski triangles, Koch snowflakes, Peano dragons, Barnsley ferns, Mandlebrot and Julia sets and other geometric constructions are very regular. Of course you are correct that this geometry was born to describe things in nature, mountains, clouds, rivers, trees, circulatory systems. These are two very different kinds of things, trees and Mandelbrot sets. So what do they have in common? I think it would be better to say self-similarity, complexity derived from repeated application of simple rules, is what unites them rather than irregularity. The same mechanisms that make a tree trunk apply to the branches, twigs, and leaves. I'm not trying to pick nits, I hope it didn't sound that way, I reply because you have brought up some interesting topics. I'm not very good at talking about art, I haven't heard many who are, but I'd be interested to hear why others think that nature even the universe has chosen fractal processes for creation. Why are fractals everywhere? For extra credit, what are the alternatives?