Distortion correction remaps the image geometry, and that creates irregular edges around the frame. The extra pixels you see with “Hide Distorted Areas” disabled are not necessarily high-quality, fully usable image area.

Keeping them gives you more image area, but not better image quality. Near those corrected edges, the software has to stretch and interpolate pixel data, and those regions can show more artifacts or reduced quality. Because camera sensors are rectangular but lens distortion correction warps the image into a different shape, some edge areas don’t scale cleanly.

So the crop is usually there to guarantee a clean rectangular image without low-quality border regions. It’s also often a conservative choice: software makers may crop a bit more than the absolute minimum so the result is consistently safe and “finished” for most users.

In short: yes, removing the crop can reveal more image information, but that doesn’t mean the image is better. The default crop is applied to hide the weaker, corrected edge areas and deliver a reliable final frame.