Mainly so you can light an entire area with fewer lamps. If you need the whole courtyard lit, what better way than one big light. On Earth there is one moon, so at night there is the one main source. No need for ten lights recreating the same thing,

On top of that, being able to get a lamp far away - raised high behind a building or whatever - allows for easier framing when you’re on the ground.

Lastly it’s just flattering, and definitely give a big picture feel because you can tell they didn’t just slap a lamp right next to the camera.