Cadets DO have their own cap badge - the equivalent of our corn flake, I wore it my first two years in Cadets. It is a maple leaf with RCAC on it. Once I learned a "trade" - ie qualified as a piper - I began to wear a regimental pattern badge. I also paraded with the regimental pipes and drums as an augment for ceremonial parades.
I see nothing wrong with them wearing the cap badge of their affiliated units - in the Calgary Highlanders, their cap badge is gold, which is worn only by recruits in the regiment, and the cadets. Qualified soldiers in the Regiment wear bronze, NCOs and officers of the Regiment wear chrome or nickle (silver coloured) as do all musicians. My only advice would be for other regiments to do the same thing if it really bothers them that their cadets wear the "same badges."
What is the point of a cap badge to begin with? It is not a trades badge and does not designate a trained soldier, it represents membership in the regiment, or to go beyond that, the regimental family. Trades badges are worn on the sleeves and combat veterans are discernible by the campaign ribbons on their DEU.
I may be missing combat_medic's point, I am at work and not reading very carefully...I thought the issue was that some cadets were seen wearing their uniform with pride, and others were deriding them for being "just cadets." I wouldn't have much respect for anyone who said they were "just" anything. I remember an NCO telling me once I wasn't really in the Army, "just" the Militia. Never been in a war, don't plan to, but then again, if I was intended to I wouldn't be in the Militia....now would I.