After re-watching the 2011 Hungarian GP, I saw that the paint on the side of the circuit is very slippery in a wet rack and it has caused lots of accidents.
One that comes to mind is the accident that caused the death of Allan Simonsen. The Aston Martin driver put his two left wheels in the paint at Tetre Rouge which resulted in a very hard hit.
There are lots of other examples, in both cars and motorcycles. Jorge Lorenzo put his bike in the white lines and had a high side, which broke his collarbone.
The white lines are necessary, in opposition with the paint outside the circuit. We are in a period when speeds are getting lower because of safety, I believe that paint is a big danger. What do you think?