The benefits of a light roast all depend on the qualities of the bean. Poor tasting beans become their best with darker roasts. Its the best way to make crap coffee drinkable. It does this by mostly by the maillaird reaction and the carmelization of sugars. Makes the cup sweeter and pleasing. The problem is you lose a lot of the more delicate flavours with the heat.

Light roasts let a lot of the delicate floral, fruity flavours shine through without getting destroyed by the heat. If you want to taste jasmine, peach, blueberry, cocoa and others, a light roast shows you what the coffee is capable of.

Most beans aren’t worthy of light roasts. Medium and dark brings out their unimpressive best and its the default for commodity grocery store coffee.

Great beans have more potential, and only light roasts let it shine through. Ethiopian, some kenyan and Burundi etc & Jamaican blue mountain are some of the most consistently rewarding for light roasts. Brasilian coffee is one of the most consistent for medium roasts, IMHO, and everything else is less common amd goes to medium dark roasts. That is not to say every region can’t produce special cups, but that comes out in the cupping and grading process.

One last quick comment about processing. Growers can dry their beans using a variety of methods. Dry, washed and fermented and others are being invented all the time. They too will impact the potential for flavours. It all comes out in the cuppings.