Why is the inside of the balmacaan coat pocket open all the way through to the pants?

In addition to the standard function of holding items, the side pockets of the ARTS&SCIENCE balmacaan coat also serve as passages for your hands to reach inside^[1]. While looking like ordinary pocket openings on the outside, they feature a slot pocket structure with slits inside so that you can put your hands into your inner pockets or the pockets of the pants you are wearing even while the coat remains buttoned^[2].

These pass-through pockets are a classic overcoat detail designed to let you handle belongings inside your pants pockets without opening the coat's front buttons when cold wind, snow, or rain blows in. While adopting the rounded collar shape of vintage coats, ARTS&SCIENCE also incorporated this traditional pocket specification for thrusting hands inside into its balmacaan coat^[3][4]. Even while walking in a long outer garment, you can conveniently manage your belongings without having to pull back the front flap every time.

hmmm, this is a functional consideration that comfortably aids the wearer's actual movements without disturbing the neatly buttoned exterior appearance of the coat.