Whenever 2D background art, instead of a 3D scene, is shown in the main menu of ow 2 the resolution of that background art is always affected by the texture quality settings inside the video settings. This does not make a lot of sense, since even people that play on low texture resolution might want to enjoy a crisp artwork in the background, instead of getting a 140p pixelated and blurry image.
For example, right now, the main menu shows a Gundam Wing artwork with low resolution.