I have played two car games on PS4 and their cars are all "premium"! Sure, there aren't as many cars as GT6 (or other past iterations) but the rest of the graphics are a lot better.
Granted, PS4 graphics v PS3 graphics is a sort of null topic but, when you think about the gradual expansion of the amount of cars included with every release of Gran Turismo over the years and how that has had an impact on the graphics compared to other racing games on the same platform, leaving out standard cars is a no-brainer!
From a photographic perspective, most standard cars have "jaggies" that cause frustration to the point where you either take the photo from a distance or just give up all together! Having standards is also taking away from the graphics which ends up causing squares around the sun, reflections of the sun or even the cars' headlights.
Having scenery "pop-up" out of nowhere or disappear really screws up photos too, as does a vehicle's wheels burying themselves into the road, wheels popping through fenders or, scarier still, cars merging in to each other or "solid" walls!
Take it back to a maximum of 700 cars! Get rid of cars that are doubles like nearly ALL of the Mazda Miata/MX-5/Eunos Roadster variants! Lose the Kei cars! (Seriously - who DREAMS of driving one??) Spend time on graphics and sound! Most of all, start showing some respect for other international manufacturers! (Australia's Holden, Ford and Chrysler branches made some of the best looking, best handling and fastest muscle cars in the world! Even Turn 10 have been releasing some iconic Australian muscle into Forza over the past couple of months...)