Dwarf fortress has main races such as Dwarfs, Elves, Humans and Goblins but it also has semi-sentient species such as antmen and ratmen; They couldn't interact with the player very much but they had a basic culture and they even had hierarchy's and ethics! (The antmen had a queen, warriors, and worker, they could use basic tools and they had a nest!) I think it would be awesome to be digging in your plant and finding one of these nests for a random species, you wouldn't be able to communicate but maybe you could help them or steal from them.) Just an idea, understandable if they don't want to add more species but I would be cool.
probably already said, i just skimmed through the comments, but it could be implemented somewhere in the quest line, or maybe they will implement side quests
"Og monster or Catstrofic event" jeez, I never knew cats could be so dangerous! Sorry, my algorythms are set to correct spelling and grammar. Catstrofic or. meow KABOOM!