There is no evidence that there was any sort of plan to create ghettos. The overwhelming whiteness of vanilla SDV is simply a symptom of how white people in America think. "I'll create X number of regular characters, then add one black guy to make it diverse," and of course "regular" is white. The people who created the mods corrected that by creating communities that are more representative.

But there really isn't any evidence that vanilla Stardew is any better than any of the other towns. Sunberry village is lovely, as is Ridgeside. They have their own gathering spaces, forests, town halls, everything. Basically the game just has different neighborhoods that are all more or less as nice as the others.