Colonies mod is really cool an its closest you can get to your idea as of now. I highly recommend it.
I agree! With maybe creating an empire with its stats (capital-world, population, ...) modifiable, maybe?
It's nice to have that idea, of building a new civilization, and it should wield many rewards, such as gaining blueprints for crafting your racial items or influence allowing you to be able to get party members and have guards trust you.