The danger with the oven installed below is looking into the oven. The door is fogged up, and then the door is opened while bent over. You know it: one hand resting on the countertop, side glance into the oven, and then the door is opened. The head is dangerously close because the door is usually opened while standing sideways and bent over. Observe this. It is different with a built-in oven at a higher level because the viewing angle to the food is different, you stand directly in front of it, and automatically step back a bit when opening. For me, besides convenience, this is a reason always to choose a built-in oven at a higher level.