“Now you might say that these are just cherry-picked examples, and that modern hardware handles models like these just fine. And you would be broadly correct in that, but the problem is that all of these relatively small costs start to add up, especially in a city builder where one unoptimized model might get rendered a few hundred times in a single frame. Rasterizing tens of thousands of polygons per instance per frame and literally not affecting a single pixel is just wasteful, whether or not the hardware can handle it. The issues are luckily quite easy to fix, both by creating more LOD variants and by improving the culling system. It will take some time though, and it remains to be seen if CO and Paradox want to invest that time, especially if it involves going through most of the game’s assets and fixing them one by one.”
IE: The the game would have looked nearly complete even if none of these meshes where in use. Meanwhile the buildings themselves are optimized.