i have been thinking a lot about damage, but one thing always comes to my mind. Tyres, and tyre modeling is by far more important then damage, cause if we would have day/night cycles and weather effects, tyres need to be remodeled or recoded so that they react properly on temp, rain etc.
Because right know tyres are modeled quiet simple (correct me if i am wrong). we have n1,s1,r1 models, and they only have grip level. But grip is changing throughout race, and weather, moisture, temperature etc. So this is where my big concern is.
Damage should be optional (both mechanical and visual). We don't need to see car de-integrating into little pieces, but some parts should fall of (rear wing, spoilers, front spoilers etc.) this was a bit off topic. :-)