Selnor is at it again))
He would justify even if Forza 5 had 5 tracks. Answer would be - "look at the CGI (a.k.a "ingame footage") that Turn 10 feed us.
I remember launch trailer with Forza 2. Where they show your wheels break loose, tires deforming, all in glorious graphics. Total BS after that in game itself. With HD version of Forza 1 visuals.
Oh, and having a lot more additional cars to choose from, but with worse graphics or not having that choice at all? I'll always choose first options. It's race sim, not contest of which cars is more detailed. And those low-pol cars have better physics than Forzas 4 or 5(as it seems in videos) exclusive over-saturated-beasts.