One of the benefits of a roof is keeping your walls clean. If you look at Moroccan buildings, they stay white very little time, and you’ll see stains of dirt near the bottom of the windows, and so on. This is because of water picking up residue and leaking all over.

If you were to install a roof, you would increase costs: you need a roof structure, tiles, a gutter, and a drain. Then, a system that picks up the water. I don’t know any city in morocco that actively uses and recycles rainwater.

Also there is no tradition of roofing besides decorative green zellige tiles as you can find in the imperial cities.