This game is absolutely fantastic on paper. You build whatever you want, however you want, and there's plenty of land that you can shape and form to your liking.
But there's no real objective. For someone like me who doesn't enjoy non-immersive public servers filled with garbage plugins and blatantly stupid creations, and to be bothered by other people at that, this game ends up being quite bland. I play mostly with one other friend. We created a broad world with various buildings and stations and what-have-you, but once you're done with that, you're left asking yourself, "Now what?"
Yes, you can kill animals and what-not, but there's no actual objective. There's no reason for doing what you do, aside from simply building it just to look at. On a grander scale with a large amount of players, I can see it doing well but only if the server you're in isn't of the likes of which I mentioned above, where it's simply just not immersive and or held to a strict set of theme-based rules.
My suggestion?
Add an enemy or something. Perhaps a togglable enemy which spawns and that you compete with, that is in terms of life or death. Some games have zombies, others have natives which attack you, or even full-fledged factions which wage war upon you.
Perhaps incorporate NPCs which may fight against you or serve under you in your townie creation.
The way I see it, there's nothing to do besides grind and build, and then you're done after you get bored. The developers have already added a plethora of weapons and other updates which could be useful towards this idea, but there's nothing beyond that.
Just a thought. If this game had some sort of enemy or objective that could be incorporated, I would definitely still play it.
Instead, I built a town with my buddy and we sort of just abandoned it out of boredom. If I'm blunt, the game is only fun for so long until you create everything that you can. After that, it's not fun at all.