One of the big limiting factors for game development is finding quality software engineers. Procedural graphics is a time consuming feature to add, and usually requires engineers to do it. Also, many of the best artists aren't as technically savvy. They can take a while to get used to new tools and techniques. And finally, it's not even that uncommon. Most AAA games at the very least use animation retargeting. Plenty of other procedural graphics techniques are also commonly used behind the scenes by artists too, such as plant generation, texture synthesis, stuff like that. It just is exported to regular textures and models before it reaches the game engine.