My best guess is that someone saved the texture as DXT1 without being fully aware of how to use the best quality preserving options.
Either that or they first saved it as JPG or something silly like that. Dark RevenantX's explanation is also possible.
There are a few textures which have tons of dithering effects (check Levy/Fenris diffuse maps as an example of this) but yeah, that's pretty bad as far as retail -> DXT1 conversion goes.
And Hades, it's the same texture, the only difference is that the MediaVP texture is changed to a texture ratio of 512x512 (which by the way also eats a bit out from original resolution - better option would be 512x1024 or even 1024x1024; DXT1 compression gives 1:6 yield so even if the texture is four times larger, a DXT1 compressed, 1024^2 texture is more efficient than a 512^2 non-DXT compressed texture... plus the compression artefacts don't show up so clearly), the non-mapped areas have for some reason been filled with black, and it has been (badly) converted to DDS.
I did a little test with the original texture, and sure enough saving it as DDS results in much clearer texture than current MediaVP texture.
Thankfully (or not) there are not so many ships that use retail mappings any more - mostly Vasudan ships that have not been re-modeled, re-mapped and re-textured. But yeah it would seem that a quality inspection of the goods compared to retail source data is in order...