^Wouldn't that scene also indicate that the viewscreen IS a window?
Oops...you're right, that scene from "Requiem for Methuselah" probably just shows a camera angle from the port side (maybe the same one usually used for planet views on the main viewscreen?).
Frankly, I'd also love the viewscreen to face front, but when the original VFX model was built, somebody felt the urge to put this "bottleneck" between the turbo shaft and the bridge dome
(i.e. a turbo lift cab in the shaft couldn't move forward because of the bottleneck).
OTOH you had this black rectangle on the bridge dome which might be a transparent window reflecting the scenery via mirrors or else onto the main viewer below.
Looks like a rotating bridge platform would be the best compromise to make everybody happy, although that would inevitably limit turbo lift use.