Trailers sound cliche all the time. When you cherry pick lines of dialogue for a sizzle reel, you pick the ones that catch peoples' rather short attention spans. I imagine they chose the lighting to help with whatever tone they're going for. I can't say I notice this lighting in tons of other movies, but then again, I don't really look for these things. Maybe they thought a more vibrant colour pallet would distract from the issues they're discussing? They might think it's sending mixed messages. I don't really know, I'm not a film maker. Are you (genuinely curious since you seem to pay a lot more attention to this stuff than the average movie goer)?