If possible, a separate option for each worldgen feature would make sense: limestone, bluestone, marble, white oak.

If worldgen is disabled, there should be alternate ways to get these items - e.g. oak sapling + white dye = white oak sapling; 8 stone + light blue dye = 8 bluestone; etc.

@BrekiTomasson that would be great if you do it
@Brandcraf06 I also support this cause I don't want world gen and only want decorative blocks
Also it would be great if world gen configs were disable by default so those who want world gen can turn it on

I second this request, especially since Blockus-generated stones are WAY too ubiquitous, some of them have 10 to 100 times the generation chance of vanilla "special" stones such as granite, diorite, andesite,... !

has this still not been implemented? :(

Just wanted to chime in to add my support for this suggestion. If you want, I can write a pull request that adds ModMenu-support with a toggle for the various worldgen features. Just let me know here and I'll take care of it.