I'm with Egg on this, I believe any block/item that can be normally obtained in vanilla MC Survival should have some way to obtain it. I feel when players aren't able to get items they could normally obtain it's almost as if a feature of MC itself is taken away. I can understand why enchanting and potions are disabled for now, but I don't think we should be restricted from access you Endstone just because you want it to be a rare prize :\. And I believe some players actually want to build with some Endstone, and need quite a bit of it.
I also apply this thought to Mushroom Biomes.