Well since '90, I've heard different "excuse"s from GW why to paint Their Toy soldiers in circus colors ...
IMO, the bottom line is bright shiny colors attracts more "kids". So that increases their perspective buyer audience. Like G and PG movies will not only get Mom & Dad to go but the kids too. So in both cases it's about profit. As after all, that is why GW, FW, the movie industry, etc., exists to make $$$$. I'll have to base this paradigm on having 2 business degrees from a state university (YSU). And having run a business or two.
But I could be wrong. After dealing with GW/Epic since '90, their business model sometimes does not always make sense to me. If any of my Mutual Funds had GW/FW in their diverse mix, I'd have my broker sell ! ASAP !
Now otherwise, I like camo and camo works, IMO. The reason all the 4 US branches of service. Now all have different patterns. Was not only to improve survivability. ( I don't know what the USN's Aqauflage does ?) An Infantryman's priority is to not get killed. But so the media could tell who was who. As at one time while I was on active duty, all branches wore the BDU. But now ... No one wanted to be miss ID'd, especially the USMC was frequently called the US ARMY and vis versa.
As far as the enemy being afraid of the USMC. If you notice, unless you are on top of the soldier. You can't tell much difference between camo patterns. [Of course the media is up your butt, so they should be able to tell ?] But the important thing is that camo helps the soldier blend in with his (or her) surroundings. Add good field craft, camo, cover and concealment training you will increase your chance of survival. And live to kill the enemy, as that is why you are there, Yes ?
As far as woodland camo MOPP suits in the desert. That is better than not having a MOPP suit or a Chem suit in orange, red, purple etc. ... We didn't have camo MOPP just OD Green.