I think that adding more optional buildings would be a great way to do this too, you could have really developed city-like islands and very simple rural ones, it would add more variety and I'd love to see how people would arrange them, stuff like that.
Yoooo, I never thought of having OPTIONAL buildings like that. I literally got excited just thinking of the possibilities for people's islands and my own. AHHH NOW I WANT ALL OF IT.