GA aircraft windscreens and side windows are not out of glas but plastic, similar to plexiglass. It brakes and diffuses the light very differently to glass in a car or house and often it has scratches and mud on it. So when I fly in the sim I have pretty much the same problem as in the real airplane, I can’t see a thing. Usually you’d have a cap and sunglasses or you can clamp charts in the window frames but the sim doesn’t offer that. So it’s not wrong what we get here although it certainly makes it difficult.
THE thing influencing a flight the most is the weather. We finally have a great atmospheric simulation and amazing lighting. It needs to be fine-tuned and some things aren’t working as expected yet but the light is one of the best features of this sim. Now make it worse just to not have to deal with the sun anymore? I wouldn’t want that. It always bothers me in P3D that “too good” weather had no impact on my flight, in reality when there is no cloud in the sky I usually don’t take a plane with a full glass canopy.
So as suggested above a sunglasses simulation (click and put it on, not change the settings) would be a great addition. But not turning down great and realistic effects.