It's probably not so much of an issue for most people, but I use a compact laptop with a smaller keyboard layout and the arrow keys are small. The main issue for me is not having a full size keyboard on this laptop. I definitely was not suggesting you to change the behavior of the application, specifically for me, as normal operation of up/down is useful and required. I was hoping that there could be a configurable option in the setting (if others have the same issue) or I would be happy with changing a registry entry if there's one mapped to these keys
I never realized what the actual up/down keys did since I disable the setting to automatically browse sub folders. In the event that people like myself disable sub-browsing, the up/down key to switch previous/next folder doesn't really apply.