For three reasons:
First, the RCAF always thinks that everything is about them, thus their involvement;
Second, the RCN thinks it's the end all be all when it comes to fashion (Hey! We introduced single earrings for people who identify as male centuries before it became fashionable), hence their involvement; and,
Third, the Army couldn't keep a thread going for 18 pages discussing a uniform they hardly ever wear.
P.S. Kilted: Air Forces and Navies all around the world, which are not "unified" like Canada's, wear their respective Army's combat clothing when the situation warrants. This is not just a Canadian situation.