Is listening to music or watching the last 5 minutes of a movie really that important to your eyes, compared to a safety risk? Of course, SQ is a safe airline (knocking on wood) but saying that chances for an accident to happen are minimal is just not realistic. There is no zero risk rule, be it on a train, in a car, or on a plane.

This happened to me on the last flight: I had my headset on and I suddenly stood up. I give it to you that it's not a big deal but it still is one tiny obstacle that could come into your face when, I wish that will never happen, you need to suddenly run out of the plane, get the cables entangled in your feet etc... Yes I know, this is a very extreme scenario but it's still very likely to happen.

Being deprived of 5-10minutes of entertainment during a few hour long flight is not that hard to endure, is it?