Why the -J- shape if ..

Someone using my RMS, a person not knowing a lot about a rocket just told me that he had been closing off the feedingtube and started putting the wood in the tunnel via the opening (see the flash on the image). I haven't seen it but he says it works. Although I don't think it is  good idea because the RMB is not made for this.. But why do we feed a RMB from above (J-shape) and not from the front?

I think the main reason that I've gathered over a few years is...

...you can feed it from the top, meaning gravity is your friend in keeping the wood moving, and burning more often, with out much human intervention, than you could achieve otherwise...
...it's space altering as well... it looks nice.  
...I think it adds a nice opening that you can shut off, as needed, by putting a few bricks on top.
...It's also more of a container for the ashes as they get going... any puff-back isn't going push the fire/ashes directly into your house.