You can't make GT a niche game for only a select group of people who have "X" specific desire. That's why there are PC sim games that allow extensive modding, like adding buses and LM cars that aren't in game. Try those if you wan't to experiment such an specific desire. But GT is a console game, designed not to cater the taste of a few but the taste of millions of people,
It already is, we have so many different sort of cars in the game. Few of them are even less exciting than vans, schwimmwagen for example (though trying not to roll it gets kind of fun). Most of the cars in GT5 are pretty much cars anyone can drive in real life. But that's just what makes it so fun in my opinion, can compare to your real life car and see how it would handle when tuned/upgraded. Or if you don't want to crash your car on the Nordschleife in real life, can just drive it in game.

Could even practice in game if you would go try it in real life.
Just because the motoring scene is aiming in the future towards a future that's not as exciting and romantic as the present one, we should suffer it in your fantasy video games? I don't know the rest of people, but personally I'll pass on that. Also, in the future we'll most likely depend on public transport for transport, so why not making a real bus riding simulator in that case?
Exciting and romantic? Not much difference between a gas and electric car really, just no loud sound (and many others in real life but talking about in game ofcourse). Doesn't make it less exciting for me. Anyway, you don't have to suffer, just don't drive the eco cars. Other people are happy with them, me being one of them.
and the thing millions of people want is their dream cars.
So what if my dream car happens to be the Tesla Roadster? Sucks they messed it up, but I still love driving it. Win often with it too in same PP online races.
Seems like you only want the cars that you like in the game, but other people like different cars. Don't see why they shouldn't be in the game. Many cars in the game that I'd never drive but I'm still happy they're in the game so people who do like them can use them.
I'm all for vans, trucks or anything else you can race with on a track. More variety makes it more fun.