Colors look improved, though I can't tell if I don't see it in game. It always is a matter of adjustment. As reference, you could take a look at BIS textures for e.g. the civilian Mi-17 which is also mainly white. OR you could just make the chopper in a different color, police choppers often have a different color than the cars. But adjusting THAT color is basically the same problem (most colors appear way too over-saturated) ;)
My textures are (a little) low res because all my Police Mod will be about 10Mb, if I use an high res one texture will be 10Mb! So It's better to download my Mod together my missions! (otherwise it could be hard to download 100Mb for mission!).
Well, I personally have no problem to install a mod once and then download the missions extra for it when I get a better quality in return. But of course, your point is valid, having everything in the mission makes it much easier to find people who play a MP mission. I do think however that the Steam integration makes it much easier today to install any needed addons than it was back in the days.
But resolution is always a problem when only one big texture is applied to the whole object, instead of having additional small textures for decals, which can then be of much higher res. But without access to the model itself, that is of course impossible.