For complex static procedural effects, such as a planet surface, you’re better off generating the textures as this means you only have to render them once and you don’t have to be able to generate them in real time. This allows a lot more complex and realistic effects than you could manage purely using the material editor.
You would likely want custom materials to actually render these procedural textures too and make them look at good as possible, but the procedural heavy-lifting should be outside of the actual material rendering wherever possible.