Do it for the feedback.

Breathing through your nose add up to 50% more resistance. That can provide more feedback for the muscles involved, more notably during inhalation. Parts like the diaphragm and the rib musculature get some more action. 

The active expansion can increase the room you have to breathe. The resistance will increase the strength and control you have within that space. That combination can create a usable workspace to breathe. That foundation can help enhance your cardio/respiratory development and control over your autonomic nervous system.

Any magical benefits of breathing are limited to the space you have access to and the control within that space. Much like other tissues of the body, they respond to force. Increase the feedback, increase the force. That will help stretch and contract the muscles, which leads to adaptation.

It’s not suppose to be easier, but it will become so.