It seems likely to me that it's an expression of L'appel du Vide, or The Call of the Void. You ever stand at the edge of a tall building or bridge and feel the urge to jump? It's that feeling. One hypothesis is that our brain does this as a way of making itself more aware of the risk. It makes sense then that when we see a small and fragile thing we wish not to damage, it would trigger this mechanism.