WOP uses a lot of cheats to trick you into thinking that the terrain is good, when in fact it's pretty fake. First they use that annoying vignette to make it look like an old film, you can turn that off. Next look at the view distance. Looks like you're flying over modern day Beijing with all that fog. Next the colours are exagerrated and in some cases washed out to look (at the same time) more vibrant and toned down.

It also relies on the FSX terrain trick of having the "ideal" altitude for terrain detail. The textures you will find look best at the altitude you spend 90% of the game at. When you get lower they look all stretched and very low detail. Load up the Slovakia map in IL-2 and start buzzing around at 200 feet. Doesn't look so good now does it? Same thing with WOP.

All flight sims suffer from this exact same problem. Even COD to a certain extent. In order to get rid of this issue you'd need ground textures to be a lot larger and more detailed. This would be both extremely time consuming and also it would really tax your system or require LOD settings that would really break immersion when changing altitude.

Look at this pic I'm posting below: It's the first pic that would load properly in GIS when typing "wing of prey terrain" with large pic settings.

Do I really need to explain why this is does not look good?