Layouts are dumb anyway IMHO.
It makes things just worse, if you make a mistake and crash into those tyres they fly around in all directions(and easier for the one who crashed into tyres to roll) and there's a possibility that those flying tyres are going to ruin another ones race, where as if there are no tyre walls on the chicanes the car that made a mistake will just fly through the chicane and hit the wall, and ruin only it's own race. Yeah ok, a follower might get taken out too, but it's easier to predict where the car is going to fly off and so easier to avoid, whereas with those tyres you don't know where they're going to fly when one hits them.
If it's for preventing cutting of the track, I'm sure at least one admin has time to "shift+u" to the area and watch for any possible cuts and punish the racer accordingly. You need to watch it anyway, in case of pile-ups.