USAF Policy on Airplane Art?

I really admire the artwork done on WWII airplanes like that on the P-40 Flying Tigers, B-17s, etc. Sadly, this practice seems to have been discontinued by the USAF and the current generation of warplanes seem dull by comparison. Does anyone know the reason behind this. I can understand the need to be low-observable but surely a little artwork in this age of BVR combat isn’t going to hurt that much, or is it? I’m not proposing anything close to what the Thunderbirds paintjob, just a little nose art.I think it would do wonders for unit morale though.