My guess is to create better sub pixel information when stitching the image together.  
<a href="https:&#x2F;&#x2F;en.m.wikipedia.org&#x2F;wiki&#x2F;Sub-pixel_resolution" rel="nofollow">https:&#x2F;&#x2F;en.m.wikipedia.org&#x2F;wiki&#x2F;Sub-pixel_resolution</a><p>If all the sensor pixel data was aligned it could create bias between the edge of the pixel and the center.<p>Edit: another thought is triangulation for determining depth