The mountains ingame atm unmodded are so much bigger than the VGX,E3 2014,2015 hills and mountains.

I agree %100 about the grass and it's something I worried bout pre release and it never got better unfortunately lol.

%100 agree about the Flora and Fauna too. It has no rhyme or reason. It's just random gen obviously and it's ugly and bland.

Half of this game is derped due to shit creatures.

Just imagine if NMS creatures were on the same level as Subnautica!? Sounds wise, immersing wise, AI wise,etc.

Cold creatures and hot creatures need to look meaningfully different, and so on.

There should be key characteristics that each type of creature should adhere too, and then purposely break those rules to get more alien , but believable and "correct " creatures.

Back to Terrain generation tho:

What's missing is varying height maps, and even bigger height maps than what we have.

We need more flat planets, more continental type planets.

All water worlds.

Swamp planets like u said are a must.

We need a complete overhaul of caves and cave systems. They're all the same and offer no danger,save for the occasional derpy pop in crab that spawns behind you. ;)