The other problem with nose art is that the squad art we have already breaks up or interferes with aircraft skins as it is. Nose art would just compound the problem even further (which personally, I DON'T like as it detracts from the historicity of the skins).
MAYBE if HTC were to include "generic" skins consisting solely of camouflage and national insignia but as it stands now it would just make things more cluttered, especially on the USAAF aircraft, many of which already have extensive artwork.