<< who cares, you can control the tray with your computer anyway. >>
Unfortunately most drives are only easilly ejected with the computer. Ejecting is simple, the problem comes when you want to put the drive back into the machine. It is the same idea as if you bought shoes that had the laces on the sole. When you are standing, it is just about impossible to untie your shoes (the same goes with a CD/DVD drive with the tray sitting in the way of you being able to reach the button.)
<< i have a feeling that if they were above the tray we'd have a similar thread asking why they weren't below the tray. >>
You might, but the number of people with the drive sitting above the person is far less than the number of people with the drive sitting below the person.
<< Does anyone actually use the eject button to close the tray? >>
Far too many drives are poorly built. Their motors can easily fail if you push the tray closed. That is the point of the button, to activate the motor to load the CD (ejecting like mentioned above can be just as easily done by the computer with no need for a drive button). Sure if you have a quality drive you can push it closed without any problem. But I've seen quite a few broken motors...
<< You're only talking about the difference of half an inch or so, I've never even noticed before. >>
Just for fun, put your computer on the floor. Eject the tray. Stand up. Attempt to close the tray - then you'll notice. Many of us are in that situation - just to close the tray we have to either be a contortionist or lay on the floor. A button above the tray would solve lots of problems without causing many problems at all (except for the few, few people who locate the computer above their heads).