1. The ability to upgrade existing structures (for example a grass wall to a stem wall) instead of having to deconstruct the structure.
2. More animals and bugs.
3. The ability to tame things. For example you could tame ants and tell them to collect pebbles or wax.
4. The ability to ride animals such as ants and bees etc.
5. Something to change the terrain. For example if you want to build your base in your own deep custom cave or something.
6. Different material tools, (like wood stone and diamond etc in Minecraft) although there might be I'm not too far into the game.