Procedural generation has a lot of advantages. One of them is scalabillity: if you want to create more things, you just let the computer run for longer.
If the software is good this method is insanely fast for iteration.
Because you are using an algorithm to generate the end results, you can quickly test which inputs influence the result in the way you want. This quick testing allows you to have great control over the details which is even better if the software can give you a lot of diversity in the inputs. This means you can spend a lot of time thinking about the details and overall structure of your artwork instead of creating it by hand.