A lot of people seem to lose interest when they get to the plains. I suspect this may be a natural reaction as the progression becomes repetitive. Transitioning from wood to stone etc seems significant and historical. By the time you get to black metal the mechanic is starting to feel tired and the resource contrived.

I would like to see further development of existing biomes. I really enjoy the plains, black forest and mountains. They are quite beautiful and pleasant. I like the aesthetic. I have little interest in the ugly eternal night of the mistlands.

It would be interesting if new resources and challenges in these early biomes were unlocked as you progress. The raid mechanic helps, but is limited in its entertainment value.

Tl;dr - new goals or activities would be nice, but maybe this is just whete people tend to tire of the game.