What is your problem exactly ? Everyone can like what they want, and that has nothing to do with age. I don't like all tuned cars, but I do respect the work put into these cars.
You miss the point of it all. People who are serious tuners don't care about performance, but about looks. Also, not all cars are shitty cars, last time I checked, Skyline's, Supra's, RX7's and so on are not really cheap.
Also, great generalizing you're doing here. The only thing you are saying is that tuned cars are nothing more but trial and error, there are lots of tuning company's who make show cars.
Face it, from all company's that were in the running, Codemasters is definately the best. They listen to the community, give enough info ( even the devs answers questions on the forum ), and I've never seen them claim GRiD would be a sim.
GRID's handling sure is better than F1 game on the PS3. There are some openwheelers in the full, so that should give a good picture of the handling for the F1 game.