Koala pouches: well designed

Does the iconic Australian Koala have its pouch ‘upside-down’? This might sound like a silly question, but some biologists have claimed that the Koala's downward-facing pouch would work better if it faced upwards. They argue that the Koala pouch is only facing downwards because of its alleged evolutionary relationship to a wombat-like ancestor. However, Koala pouches work extremely well in their current orientation. When Koalas climb trees, as they must do to feed, their bellies rub against the bark. If the mother's pouch faced upwards, it would fill up with debris. Moreover, the rear opening has soft tissues and a ring of muscles that hold the young ones in. The pouch also secretes antimicrobial proteins to make it nice and clean just before it’s due to carry a new young one. Thus, Koala pouches are well designed, not poorly designed, as you would expect from the Master Designer. They do just what they were designed to do.