Their similarity isn't very noticeable; I never paid attention to it.

Their DIFFERENCE isn't noticeable because it's a chaotic mess of identical blocks. You simply don't pay attention to it. Think of Inferno, Haven, Dungeon, Necropolis, or the rundown tent city of the Stronghold. Of course, no one clicks on the buildings like they used to, because there are buttons now. If there weren't buttons, Nival would be flooded with complaints. The cities in the fifth game are an eyesore, a disgusting mass of gray cubes or spires. Take any city from any previous game, and you immediately get a beautiful picture of a city with diverse buildings against a pleasant backdrop. Here, you hire heroes, but there, you learn spells. And this fifth-game, rotating abomination, looking like a papier-mâché model where different buildings only differ in size or width, or a couple of tiny details, is unnecessary.

That's why they don't make 3D cities.