I think a single copied interior would look worse. You would need at least 2, one of them a mirror image to handle left vs right hand drive. What about a wide car vs narrow, just stretch it and have the proportions wrong? Pretty soon you have several versions, none of which are exactly correct. Also, I don't want a roll cage in all of my cars, or a race interior. Just give me the correct outline of the windshield and A-pillars while I wait for PD to make all cars premium for GT6.
it probably was system limitations that caused them to use the blacked out interiors on GT PSP, just like having only 3 other cars on track. I am pretty sure that the lack of interiors on standard cars was because PD did not realize the backlash they would get for not having them. I hope they also noticed the criticism of the standard cars in general and give us all premiums in GT6.