> Is it really that dangerous for anyone to take a quick glance?

Speaking as a private pilot, it absolutely is. Even in a Cessna you're going to be travelling at least 75 mph. Possible faster if the conditions are gusty. For the last 1/4-1/2 mile at least, your vision needs to be 100% outside of the airplane. Now if you need to do that in a Cessna at 75 mph with no more than 4 people on board, why wouldn't you also need to do in a 787 that lands at ~180 mph with nearly 300 people, or an A380 that lands at ~140 mph with over 500?