Paint protection film sounds good. I have self adhesive felt stuck to the back of the belt and the major contact points of the bonnet so its felt to felt contact. Soft velcro dots where the belt touches the louvres. Been on for 3 years, no scratches. The felt is available in various colours and is removable with white spirit if required.
As for preference, well its a traditional thing, just like the rest of the car, probably originated from early track cars, flexing chassis and a belt and braces solution.
As for form following function, i don't think that applies to the aerodynamics or very much else of trads anyway thats why modern cars don't look like Morgans.
