Why Do They Sew the Pockets Closed on New Jackets?

My wife bought me a new jacket a couple years ago. I have worn it through one winter and am working on the second. It's a nice jacket made from a blend of wool and polyester. I only ever used the right pocket on the jacket until a week ago. why? the others were sewn together. I didn't like the fact that I only had one pocket but I never thought much about it. I thought the sewn together pockets were just sewn to look like pockets. I loaned my jacket to my brother n law and he put his right had in the right pocket and tried to put his left hand in the left pocket when I said...it not a real pocket. He ripped it apart and reveled the left pocket and slipped his left hand inside. I felt like an idiot.

Then today, I discovered an inside pocket on the jacket sewn together. I ripped it open and now have my wallet stored inside. I never knew. So...WHY DO THEY SEW POCKETS TOGETHER??!!