Lots of the coop designs I've seen lately have external nesting boxes, and I really wonder why. I'm all for being able to check for eggs from outside, and I have a door for that on my current tractor -- a vertical door with the hinge on the bottom, so when I open it, I am opening up the back wall of the nesting boxes, opposite the entrance the hens use, not the roof. The external boxes seem needlessly complicated, requiring some kind of weather sealing for the hinge in the little roof and probably more material fitting than interior nesting boxes. So, what is the advantage?