There are many methods and the roasts are different from a roaster to another.
People kill the gas more or less than for 10-15 sec during FC or right before. Light coffee is roasted different from normal. For more aromas you start with the lowest temp possible, and you kill the gas in the FC. FC is not so violent as in normal/traditional roast. And as you can see not all the beans are cracked, look at the surface.
As far as light coffee, you can make great espresso with it, but it takes a lot of sacrifice (money +time + practice). This is not better this is just different.
Some photos of really light roasts on unimodal burrs, with flow/pressure control and long shots.
The last photo is a comparison between full city+ (almost Italian roast) , normal espresso roast and then light roast. This is made in the same light so this is better to compare. It is not the same coffee variety.