I can see a few reasons why people would still prefer commissioning artists over using AI art.
Commercial use: Weirdly enough, a PETA lawsuit regarding an ape selfie determined that a work is only copyrightable if a human created it. This is further expanded upon with regards to an attempt at copyrighting procedurally generated music, wherein it was determined that algorithmically generated content can't be copyrighted, even if it's the creator of the software that's attempting to exercise ownership over the outputted content.
If you're making a game, visual novel, or comic, the work generated by programs like this technically fall into the public domain. Which sucks if you make a dope CG and want to make sure nobody else can use it in their projects, but $60-100 isn't that big a deal if you're making a commercial product.
Unique styles: Say you want a painting done in the style of Kaja Foglio or Quinton Hoover. Both of these artists have very distinct art styles, which would require a new model built off of their respective works. However, you may run into a roadblock where there aren't enough samples to train with, or their portfolio consists of low-res imagery.
Modifying/correcting AI Art: At the moment, there's a lot of tinkering that's required to get AI art looking just right.
Pixel Art: Current models for AI art are lackluster when it comes to pixel art. There's workarounds, sure, however for pixel art that replicates console limitations (resolution, palette, tilesets) this can be a big ask for AI art.
2D animation rigs: A bit more niche, but 2D game designers that rely on puppet animation (think Plants vs Zombies) will need characters that can be broken up into dozens of components to allow for fluid animation in their games.
Tangible artwork: Traditional artists will likely have a longer lasting stance in the market thanks to clients that prefer having a hand painted canvas. I know I'm personally a huge fan of Inkwash Watercolor art, and still pay $200+ for original works.
Consistency on fine details: Having an AI replicate things like a character's tattoo, logos and text on clothes, or the placement of freckles and birthmarks is still a bit wishy-washy. For smaller projects and indie commissions, I could see clients hiring artists to place these types of details on AI generated artwork. I'm sure this'll be made redundant sometime in the next few years, but for now I can see some issues.