Speaking from personal experience and observing passengers in China, I've noticed that people like to deplane to a bridge. It is also safer in hard weather and avoiding people from tossing stuff towards the engines (yes, this is a somewhat uncommon but not unheard of occurrence in China to pray for "good luck", supposedly):
This obsession with air bridges has grown to a point that obnoxious things like this are being built in PEK at remote stands (picture stolen from Chinese "Twitter", Weibo):
