Some interesting points you got there.
It is the Turbo-version i've driven and the track was very hilly. And looking at the topgear video i can see that Jeremy also has troubles in handling the car. The interesting thing will be if there'll be some cars that will be more unpredictable in Assetto Corsa - for example the old M3-BMW - it should (i guess) be more unpredictable compared to the more modern cars.
In your first post you said
"I have been driving some cars on track, and in fast cars you have to wait for the car to point straight ahead before pushing the throttle."
In reality even with race cars you can apply and often do apply the throttle with the car in various angles and balance the car with steering and additional throttle inputs / variations.
You can clearly see in the video above (radical video) where the guy is over driving the car that he is well on the throttle whilst at an angle and whilst also on the dirt but he is still able to use the steering to stop the car from spinning around.
Its actually a massive short coming of many simulators in that the cars don't drive properly on the limit / don't handle right when on the power or at angles.
This is what NKP is famous for getting right along with other games like Game stock car where a skilled driver can use balance and car angle to be more creative in how they approach a track and achieve a good lap time.
You also say
" old M3-BMW - it should (i guess) be more unpredictable compared to the more modern cars."
To the contrary I think older cars are often more predictable in there profile its just that they are heaver and have less grip so tend to slide around more and are less responsive. So you have to have a good knowledge of what sort of arc they would get into on a given corner and adjust brake distance / slide expectations.
Though obviously it will vary from car to car and also be dependent to how you are driving each car and the given track and circumstance you put a car into.
All cars I think have the potential to be erratic or unpredictable in given situations , I guess modern cars are probably easer to correct though when that situation does arise conversely you are probably more likely to put yourself in that situation with a modern car as you are generally forced to drive older cars in a smoother way to get the most from them.
Above is more of a generalisation though I have no idea what the old M3 is like compared to the new one maybe it is more unpredictable
, also some people will maybe gravitate to liking or finding x car easer and more predictable for them than Y car.