We haven't shown the GM giving any explicit descriptive background (as distinct from NPC dialogue) for several strips now. We could spend a lot of space with GM narrative boxes saying things like:

While you stand on the balcony, overlooking the horizon-wide sprawl that is Coruscant, with vast fleets of transports plying carefully delineated criss-crossing commuter routes above the towering art-deco skyscrapers, the blazing orange sun sets slowly, painting the sky in a glorious array of warm colours, which bathe the scene in a spectacular glow.

But really there's no need, since you, the reader, can see that that's what happening. And we think it's far better for readers to see the pictures than to have to read masses of descriptive text that (a) cover up the pretty scenery, (b) merely tell you what you would be looking at anyway if only the text boxes weren't covering it up, only in less detail since a text description can never convey everything in an image, and (c) interrupt the flow of the dialogue.

So that's why we don't do it. You should, however, understand that the GM is actually describing these scenes to the players, so that they are aware of the things that we can see in the images. We're just using the convention that we don't have to explicitly burden you with the GM's lengthy scene-setting descriptive prose. (This also explains how Obi-Wan knew there were no railings in Episode 128.)

Transcript

Qui-Gon: I wonder what challenge rating those senators are.
Obi-Wan: We're not going to attack them.
Qui-Gon: Oh, chickening out, huh?
Obi-Wan: That's not our mission. We need to save Naboo from the Trade Federation and recover the Lost Orb.
Qui-Gon: Hmmm. We'll need Jar Jar. And Annie.
Obi-Wan: The Jedi Council might have something to say about that. Your little medical experiment might cause unforeseen problems.
Qui-Gon: What's the worst that could happen?
Obi-Wan: I dunno... Premature baldness?
Qui-Gon: Hmmm. That would be pretty bad.
{beat, wide shot of glorious sunset}
Obi-Wan: Nice sunset, by the way.
GM: Thank you.