Melokhy: If they need ideas to add weird creaturees and/or trees, i have enough ideas to call it patch 3.0 :p
I think more diversity is coming sometime in the future, because there is such a great demand for it.
But remember, each time they change the procedural generation, it causes problems for the players.
Foundation, Atlas Rises, and Next all brought us universe resets to add in new stuff. But players awakened the next day to discover some bases underground, high in the air, or their planets changed biomes, like from tropical to radioactive, and so on.
The Abyss did not reset the universe, because the underwater areas are governed by a different parts of the software than the land areas. So they were able to change the underwater areas and leave the land untouched, but there were still some problems for players.
So more diversity is probably coming, but only after HG works out how to help the players with their problems, ie a new in-game technology, or an option to "rescan" your save file, or some other such thing.