CX (and other airlines) have effectively banned daytime flights (i.e., the perceptible experience of taking one) for some time now. You have to remember that the reason you're flying is to enjoy the in-flight entertainment; getting to your destination is just a secondary objective. And it's not like the screens can't be seen if there's daylight coming in anyway, but nevertheless internal darkness is what the airline has apparently decreed. Actually, the sun police don't come around till some time into the flight so you can probably enjoy a good hour or so looking out the window, and no one's going to accost you for taking brief peeks during the flight.

Frankly, as far as I'm concerned, there's nothing nicer than a daytime flight with natural light streaming in the windows. There's a beautiful atmosphere about such a flight that I've always enjoyed, and it sure makes reading a book (something I like to do on a flight) much easier and more relaxing than the pathetically weak artificial light that issues from the overhead lamp. I honestly don't know why they have to be so imperious about this. Surely they can leave it to the preference of the passenger on the window (who after all may have asked for the window seat precisely so he can enjoy the view).