5 Answers

1) to watch breath taking views when landing in airports like Hong Kong & Tokyo.

2) Gauging outside as to when to brace for impact prior to crash.

3) When flight attendants are not pleasant to look at or ones that give bad service, you can look away.

4) To differentiate my seat from the cargo hold since I am paying more for my wonderful economy class seat.

There are windows in a plane for viewing purposes. What is this word - uaeful ?

It just came to me, useful...well again one reason, they are useful for viewing outside.

You all forgot to mention UFOs. How will we know if and when we will be abducted? It will give us time to hide under our seats.

in case you are sick silly,you dont want the airoplane to get all mucky,