Hmm after looking into it more, I agree that the crafting cost for the Mycelial Boots was a bit steep on the wool side. I have reduced it from 15 to 12. This change will go live with the next hotfix for Serenitrove, and the wool repair cost will be slightly lower as well (due to the crafting cost decrease).
As for the Void layer, I added the maze-like mechanic because Void cells have 0 hardness. Without some kind of obstacle, it would be too easy to just dig straight down. The debuff zones (voidzone, black hole, still figuring out a proper name for those lol) are there to make navigation more interesting and a bit more challenging.
Thanks for the feedback, and I am glad you're having fun with the game!