I distinctly remember the ads and cars without trim rings. The idea was to make a good looking, racy looking cars at an affordable price. Trim rings would add cost. But ugh! Those whitewalls on Rallyes! Remember the idea of the original Road Runner? Good go-fast mechanical goodies without the frills. That's why Pontiac created the Judge.
Sizzlers and Twisters came with 198, 225 or 318's. Anyone who was there in the early 70s remembers the insurance rates. And a 3 speed stick or automatic was less. I was paying $1000/yr for a 4 speed 67 Barracuda.
Having said all that, I have Rallyes on my 64 and left the trim rings on the shelf. I think it makes the 14" wheels look bigger and it's just extra rotating inertia.