It is also really gratifying to see a beautiful object racing around that I got to build. E.G. I've had many static Lancia/Ferrari/Porsche models over the years... but nothing compares to seeing a 1/10th Stratos clawing for grip after a big slide.
I build models in the winter months and race RC cars in the summer. I like both hobbies and am involved in each. They are different, and I like them both for different reasons. Models are fun to build, but once they are complete there isn't much left except to go on to the next one. Its the process that is enjoyable ...and something to do on rainy days. RC cars have the added benefit of constant tweaking and competition, it is much closer to real racing.
As for a concourse class in RC, I personally think any entrant should have to be run in a class as it is presented in the concourse.