Mostly quality changes.
Garland and Seawreath give 12 rot when they spoil instead of 1 rot. The garland just isn't very useful. I would actually make a garland if I kept the rot from the 12 petals used to craft it. The seawreath is worse. You can just eat the 12 cooked kelp for -60 sanity and 112 hunger instead of crafting the hat. The seawreath only gives -63 sanity IF you wear it for 6 days straight! It probably needs a buff more than just giving 12 rot. Maybe it should be -5 sanity/min rather than -1.33 sanity/min.
Convert logs into charcoal with scaled furnace. It's just nice to have other reliable methods of getting charcoal other than burning forests, and a log-burning furnace for charcoal makes sense.
Abigail can haunt things just like player ghosts can. I think this change alone would make Wendy a pretty solid character. Haunting has a lot of cool effects people may not know about. If Abigail could haunt, I think people would catch on to its usefulness.
Small glaciers on the ocean to mine for ice, and make ice float on water like it does in real life (facepalm). Glaciers would be scattered like sea stacks, and be most pronounced in winter, and vanish in summer. Ice would make a good filler for fish food in the crockpot. Anyways, why does ice sink when dropped in the ocean? Ice is less dense than liquid water and floats irl.
Frozen *Tuna* weapon. Tuna, or whatever big fish of choice. This would be a cool weapon. Games like Yakuza, Maplestory, Dark Cloud, and Monster Hunter have a frozen tuna as a joke weapon and it's a personal favorite of mine. Crafted recipe for example could be big fish + 4 twigs + 5 ice.
Different Boats. A small, but fast boat. A fire resistant/rain resistant boat. A sturdy boat that can smash sea stacks. Lots of obvious ideas which I hope Klei's team catches on.
Boat skins. I'm tired of the wood boat's rinky dink design.
Add something to the beefalo biome. The beefalo grassland biome feels uniquely empty of anything interesting. Other biomes have very useful and key items like the bee queen hive, moon base altar, stage hand, oasis lake, dragonfly, tumbleweeds, cacti, mandrakes, panflute and glommer, pig king, meteors, reeds, living trees, etc. This biome is just a gigantic beefalo+grass zone, and that's not an understatement. Future content could fit there nicely, or I would remove the default world gen mechanic that randomly gives you twiggy tree/grass gecko worlds, and just throw the twiggy trees and grass geckos into the beefalo biome by default.
thank you for reading.