If you want to expand a map, you have to craft a bigger one by surrounding it with paper, which is only possible with a crafting table currently. I see no reason to limit it to 2x2, and keeping it consistent isn't needed all that badly.
Iron nuggets should have the ability to be crafted into arrows, replacing flint in the recipe. Maybe they make less arrows for balance, but I want iron nuggets to have a use beyond just making iron ingots.
Low durability wooden tools should have a chance to give you splinters. Splinters will act as if you are hitting someone that has Thorns I whenever you use a tool or weapon. This can only be fixed by creating tweezers using 2 iron nuggets in a recipe like shears are crafted.
I don't think I agree with the idea of splinters, but a better fix would just to give wooden tools the ability to have a handle grip, which you craft using leather and the tool.
A blizzard weather that makes snow come down visually faster and at an angle, adds a slight fog affect (to reduce visibility) and makes snow spawn on the ground faster and stack on top of each other. So it would literally bury things in snow.
Pufferfish do water breathing because they famously "carry air with them" when puffed (they can also puff with water, though). Perhaps they should offer a thorns-like status instead, while more normal fish give water breathing. I'd say rotten flesh for nausea, and for clownfish, a new status Poison Resistance. Clownfish are famous for living among the tentacles of poisonous anemones; not only are they not harmed, but they can eat bits of the tentacles and integrate the anemone's stinging cells into their own skin.
I admit, I didn't think of the air-sac thing for Pufferfish, but I still stand by my idea. Rotten Flesh is too common for nausea, and Poison Resistance is too niche, milk buckets are much cheaper and easier anyway.
Plus Poisonous Potatoes should be used to make Hunger potions, because something needs to be done with them.
Today I was running through the jungle and while I was parcouring through the greenery I thought leaf - /"bush"-blocks should extenuate the falling damage like water does. I'm not sure how it would work with the MC-physics, but I'd really like some more blocks that don't hurt the player if he falls from a (4 blocks or really) high place.
Hay bales take like 80% fall damage when you land on them, so it could be something like that. Maybe wool blocks too.
And rose bushes should hurt you as you move through them.
I know, but you probably make only one book and quill in the entire game, and I'm not sure how many people make fireworks in survival, except maybe for the Elytra. And neither of them are useful for survival, except for the Elytra with fireworks and selling written books, which are both really niche uses.
Feather Meal, the equivalent of Bone Meal but made from feathers ofcourse. It's a real thing, and can be used as a fertilizer. It would be a nice secondary use for feathers, which are primarily pretty useless beyond arrows, and a way to speed up crops on Peaceful. It'll probably take multiple feathers to make one.