Dejank really is necessary at this point. While new content is nice, most people can get new content by just loading up on mods.
There's many systems which could see some improvement atm.
Prospecting, Combat, NPC interaction, Animal Husbandry, Agriculture and Tailoring are some of the worst offenders. Deer have had semi-broken animations since they got added (specially when swimming/attacking), animals in general love to go for a swim for no reason, and will happily follow the player into water or jump off cliffs to their death, mob AI is overall remarkably stupid.
The rideable elk has extremely janky movement because it has to climb every single block with a half-a-second delay and the running noise gets interrupted every single time it leaves the ground even for single block descents. Mobs in general (including the elk) also get stuck trying to path in a diagonal line which goes along the edge of blocks, making them have to climb up the blocks then go down and up and down again (making them spin in circles sometimes), I know it's more realistic but entities should just climb blocks instantly or with minimal delay so they can path quicker instead of getting stupefied by anything other than flat terrain.
As many people have said, polish until the game could be shipped as is and then add new stuff. New stuff should be added when the foundation it lies on is rock solid.