Aside of "bringing bad void fog and bedrock particles" and "remove the pale garden from the overworld", what changes do you guys actually think is needed to fix the current state of minecraft?
Return to game direction being inspired by classic 1980s CRPGs and Roguelikes instead of whatever wholesome reddit chungus blob they are doing now. Heavily nerf elytra (like remove rocket boosting), heavily nerf or remove mending, heavily nerf villager trading, tone down all the new cave generation, either make the giant caves super super rare or remove them outright, undo the changes to ore distribution that makes diamonds extremely abundant, remove phantoms or completely overhaul how they function if they are going for you needing to be prepared, very controversial but remove sprint or completely rebalance how the mobs or sprint works, sprint broke the balance of mobs actually being a threat. Buff minecart rails heavily and expand on them, make building infrastructure the endgame.
Current Minecraft progression, under the lens of the games Notch is fond of, is essentially a simplistic CRPG like a barebones Ultima. You have a vast world, and you explore and find villages to trade with, need to enter the caves (the first 'dungeon') to get equipment in order to progress to the next 'dungeon' which is the nether fortresses to get a key item to progress to the next dungeon the stronghold, to enter space/the end which is the final dungeon and kill the boss. Expand on this, I'm sure you could do it without making it an RPG adventure mod. Maybe make villages more distinct and random, add towns too, maybe even castles/cities but thats probably pushing it for a game like Minecraft. I doubt anybody working on Minecraft now has played the games Notch was inspired by, or are even aware of the inspiration. There is a reason Notch keeps making roguelikes, and why his newest game is also a roguelike.
The original potion brewing was supposed to be randomized per world and you would have to figure out recipes, I would do things like this.