Classroom as cave?

I don't want to become that weirdo prof with the weird quirk, but I'm rapidly on the way there I'm afraid. I'm finding this term that the first thing I do when I enter any of the classrooms that I'm teaching in this semester is to open the blinds.

It's downright cavernous.

I can only assume that the instructor before me in each case is primarily using powerpoints and that's why half the lights are always off and the blinds closed. Thing is, one of the classrooms is north-facing, so there's never any glare. I've taught in this classroom in previous terms, and I can vouch for never having to draw the blinds to show anything on the screen, even in April, when the sun is higher.

I teach with powerpoints occasionally, but I'm finding this consistent drawing of blinds confusing. Part of the reason I don't use powerpoints very frequently is because I think they are structurally limiting, and students rarely interact with either each other or me when the screen is up. Another reason is that the darkness is just too much sometimes for students who are sleep deprived. I have students who have a difficult enough time staying awake with all the lights on and a discussion going on. Turning off the lights just seems to invite them to nod off.

So if the classroom is like a cave, does that mean we're presenting our students with just the shadows? I can't help but think of Plato's cave and the shadows that are just a poor representation of reality that we mistaken for reality itself.

Doesn't that sound a bit like a powerpoint? A shadow of the reality that effective pedagogy should aim at?