Hi, I might be wrong about these but im just voicing my opinion.

1: Islands/oceans "dont" generate anymore, In my experience I haven't seen any islands or archipelagos like there used to be, the first image I have is 1.13.2 the aquatic update, as you can see lots of islands and large oceans, the second image is the most recent version (not snapshot) I miss building on an island and claiming it. Ik on bedrock I used to do a challenge where I pick a seed that spawns me on an island and not leave for the rest of the game and I think it was fun but that could be nostalgia (3rd picture) 

2: Ocean revamp, With the aquatic update the oceans were improved with coral, dolphins etc, and with 1.18 the world generation changed but the oceans weren't improved with added depth. I think trenches and proper underwater caves could be cool especially with the nautilus, instead of huge coral blobs, maybe a table coral thing that sticks out from the side (not like we have rn) Also may be new wrecks and reasons to go into the depths. If the world goes down to -60\~ why cant the oceans atleast get a bit deeper, I guess it makes sense if it would destroy current terrain generation but what doesent lol. I think we need more incentives to use the nautilus.

3: Bring back magma ravines, to my knowledge the underwater ravines with magma in them were deleted for some reason, adding onto this, I feel like whenever a terrain generation feature is removed the devs dont say all that much about it or their reasoning but I could be wrong.  
  
4: remove/change saddle and nametag recipe, The recipes are great for accesibility dont get me wrong but it removes the purpose of venturing into ruins or mob spawners to find saddles or nametags? If the recipe change maybe they could add a template? so once you find one out in the wild you can make "infinite"

  
5: (dont know what to call) the tales and trials update was a good step forward for adventuring, especially with the archaeology but maybe some newer structures to explore could be nice that have more rewarding loot, maybe its just me but once I settle down with a base I tend to not go far from my base, an incentive to make camps or smaller bases for exploring could be nice.

6: Connecting minecarts, I recently played with a mod that lets you chain together minecarts with chains I think it would be an amazing idea, and maybe bring back the use of minecarts and rails, over ice boats/elytras, a functional train network with purpose other than being a slow method of travel (and fairly expensive if you dont dupe) conncecting them would be a fairly easy way to add a new feature, also maybe the more minecarts you add the slower it gets but you can add furnace minecarts to act as load boosters that let you chain more minecarts together NOT straight up speed as that would be too op, I think the max speed for minecarts could be increased a bit maybe with new copper rails???  
  
7: ok this ones a joke but END UPDATE!!!!! honestly a revamp to the end could help some mods do this well but not entirely, it could change where you spawn when you enter the end so you can go through the islands gather new loot and THEN fight the ender dragon after you are truly prepared, I mean the nether got an update sooooo long ago so why cant the end? I get its a barren wasteland but maybe expand on that add new biomes in that waste land, we dont need another color of wood or ores but maybe just some variation, I think the end "flashes" are a step forward but personally I would like to see more

  
Thanks for reading and remember these are just my opinions as a member of the community and I understand why some of these might not be added but it would be nice to not have to resort to modding the game to see what I want also I love the ocean irl lol :)

List Of My Minecraft Hotakes (maybe)