So because some cars to your eyes look similar, they should just ditch them all.
Most American muscle cars look roughly the same, may aswell get rid of them, most porches, Lamborghinis and Koienigsegg look the same.
If you applied this rule to the game then half the cars would need to be deleted.
How would this improve the game?
The reason there is so many is because they are very popular cars with a long racing history, it would be extremely weird to exclude them from a racing game that offers over 350 cars.
Maybe in the US there is less demand for them but in the UK and Europe (along with Audi) they are very popular cars.
In my opinion, there are way too many American muscle cars but I would never say they should be removed from the game.