There's a reason why this series has sold over 70 million copies. And it aint the gorgeous looking cars.
It's a hard concept to understand for some. Especially for those who never bothered to play the game
Yes, the gameplay in the first four games is mostly great. That is why the series sold so well, GT5 on the other hand wasn't great in the gameplay department but it sold well on the looks, numbers and the name alone.
I don't know why THAT is a hard concept for some to understand. Many of us are fans of GT series, we loved GT 1 - 4 but weren't impressed with the GT5 gameplay.