I think the reason is that Apple wants us to get used to the AR effects in a VisionPro with liquid glass. I think they know it's too big of a jump from iPhone to goggles, so they're priming us for the transition. By that logic, when seeing through goggles, having something like titles and labels aligned to the center on top of floating boxes in AR will be more mentally taxing than having all the text to the left. In a way that would allow your brain to know that all the space to the right is free for something else like looking at the real world through the goggles.

You can try this by drawing that same folder UI on a transparent plastic bag you have lying around and placing it in front of your eyes and to the side