true. it is possible to achieve an immense level of realism in simulation. one just has to take a look at the flight simulator's world to realize that.
apparently, though, some (most?) people are not that interested in the same level of realism and complexity in racing games. many people still prefer the instantly playable, pedal-to-the-metal, 300km/h-in-curves-with-no-grip-loss arcade racing game where you can just hit reverse and continue a race, even if you hit a wall dead on at 400km/h (unrealistic speeds used on purpose... because on those games any little Civic will pull those numbers).
it seems that the demand for an ultra-realistic racing game is NOT that high, which makes the obvious investment (in time, money and research) not very attractive to gaming publishers. from my personal point of view, it's a pity...