There's a reason that AAA open-world games like GTAV are using rather limited procedural generation, too. The problem is that to create N pieces of satisfyingl

There's a reason that AAA open-world games like GTAV are using rather limited procedural generation, too. The problem is that to create N pieces of satisfyingly unique procedurally generated content, you need M pieces of content that were carefully designed within additional restrictions to make them combineable in various fashions - making them harder to create. Then you add code to glue that all together. If you think M=0, that just means you've hardcoded your content in code. When N >> M - e.g. you're generating thousands of similar-yet-distinct roguelike levels, trees, etc. - procedural generation can pay off. But even for large-scale world assets, it's frequently the case that N < M. Making the content non-procedurally is going to be cheaper - fewer limitations to worry about, and fewer pieces of content to actually generate. A few clever tricks - rotating, retexturing, tweaking a base model, etc. - let you make a lot of non-procedural content without creating each piece from scatch, and lets you stretch that content to appear like you have more variations than you actually do.