with most airplanes, airlines included, it gets real warm at altitude, so being able to open the sunroof in flight is a bonus.
that is what they mean by a glass cockpit...
Man I kill me!!!
Truth is, your visability is so restricted in any airplane being able to look up and behind is a true luxury. When ATC calles out traffic to you, it may sound like this.
N1234-YOU HAVE TRAFFIC 4 OCLOCK, 2 MILES.
the 9 oclock is realitive to your Track, not the aspect of your airplane. if you are correcting 20 degrees to your left to make good your track, that traffic will be at your 5 oclock, not 4. if he is above you going lower, beaing able to see him helps everyone.
I think because "Way back in the day" the planes used to do long range NAV with sextents, so the Navigator needed a window that faced the stars. The 727 and the 737 are based on the 707 which is from that time. The DC-9 also has the windows on top, as I guess the DC-8 does too.
I read a article in one of the airline mags this week. It said that they were originally put there for increased visiblity in a turn. It also said that pilots hate them. Current production 717s no longer have them.