1934 Kalamazoo Peerless door question

[1934peerless]

Hello, I recently purchased a 1934 Kalamazoo Peerless wood/propane stove and I have a question about the front door above the ash box. What is the reason for it? There is a piece blocking me from adding wood through this door, It's removable though. I'm curious as to the reason I would remove the piece from the firebox and use that door as opposed to the side one?

 

[begreen]

It's a coal stove. The top part is the coal hopper with a riddling grate at the bottom.