General Mob Drop Suggestions

I think that items such as Bones and String have a very important role in Minecraft, specifically because of the ability to create bonemeal from bones and bows, traps and wool from String, but gunpowder and rotten flesh are some of the most common mob drops out there, and the only functionality for gunpowder is to make TNT and fireworks, and rotten flesh has no functionality whatsoever, aside from being edible. I have yet to see Mojang allow players to make something out of rotten flesh, let it be Leather or some other material we could make items out of. It's also worth mentioning that there should be a way to combine both of these items into some type of crafting recipe.