You're right in many ways...
It is important not to let the game get too far from its roots. At the same time it's good to have special incentives that offer a new experience to the committed gamer/driver. Personally, I prefer GT racing to F1 because of the look of the cars, but I'm glad of the chance to drive F1 cars in GT3... (I heard Kazunori Yamauchi was interested in making an F1 game and some at Polyphony want a GT-style motorbike game)