I don't know if someone responded to this already, as I'm still trying to read through the backlog...but I would LOVE the introductions of actual seasons. Though it'd kill a certain aspect of "realism," I think it'd be great to have seasons that last either 15 or 30 days. Day 1 would start Spring, and you can plant and grow, as well as through Summer and Autumn. Maybe specific plants for specific seasons, though that might be harder to track. Would make winter, where you'd only have the fewest of cold-temp plants you could grow, a serious survival push. You'd have to be using heat, you'd risk drawing hordes to your base, and food and prep would pay off if you've done it, and you'd struggle hardcore if you haven't.
I don't know how difficult that would be to implement, but man...I'd LOVE it.