1987's Test Drive had five cars. 2009's Need for Speed: Shift had more. And at the other end of the spectrum, we have GT5 and its 200 "premium" cars and its 800 standard cars. As seen on Pixel Counterrr.
For what it's worth, I can understand how some people have knee-jerk "why are there 1000 cars when at least 70 of them are skyline variants" reactions to GT5.
But what I don't understand, is how some people fail to realize that while yes, to the lay man, a skyline is a skyline is a skyline is a skyline. To the automotive enthusiast, each one, while looking similar, is actually different. Ex: Skyline GT-R. The fabled Godzilla car, it's an AWD twin turbo beast. But the Skyline GTS-T is a rear drive single turbo but LIGHTER skyline.
There are people all over the world that own different varying trims of certain cars. Those people are the reason there is such variety in the game to the point of being trite.
tl;dr if you're car stupid and only know big names then it's completely understandable why you'd be upset about "duplicate" cars. if you're a tuning enthusiast, then these kinds of differences actually MATTER.