I think possibly part of the reason they are so rare, is the fact that if you manage to find one on a multiplayer map, you may as well have an A-bomb. Mycelium(sp?) Can ruin an entire continent if left unchecked.
I personally would like them to be a little less rare. I've never found one myself.
They could add some other ways to get Mycelium naturally, like for example, you may be able to find Mycelium seeds in chests or something, but without making the Biome less rare
I personally would like them to be a little less rare. I've never found one myself.