I don't know if it has an effect or not since I'm unfamiliar with how Worldgen works in mods, but there's a Vanilla mechanic that allows you to change a slew of worldgen options, from oregen levels/amounts to "sea level" to statistical size of biomes to...
I use the feature (in the Create world tab... select world type "Custom") to stop the generation of Andesite. To me it looks too close to regular stone to be useful to decorate with and too useless otherwise