Perhaps. I don't have any information to confirm or refute that notion. In terms of biomes and where cities appear, I can agree.
In terms of city layouts, I don't. I suspect that RWG's move to districts was to try to bring more logic to POIs that appear next to each other in cities and the move to Tiles to make that happen was to improve the appearance of cities by eliminating dead space between the POIs and allowing integration of the POIs with roads and sidewalks.
Traders moving to Gateway Tiles could be either, though I think that was more of a way to scatter them out across the map.