Boy, that big window on your door sure looks fancy. And the vertical panel of windows next to your door is even more elegant. Your visitors will be impressed - especially if your visitor is a violent predator looking for easy, naïve prey.
All it takes is to break the glass or quietly use some tape and a glass-cutter, then reach through the hole to unlock the door. It's ridiculously easy. Then your home - your nest and sanctuary - suddenly becomes a huge advantage for the predator by muffling your screams from neighbors. You’ll go from heaven to hell in a heartbeat.