Its a fair point though....with a bit of experimenting you can get some different quality of sounds form your guitar...closer to the bridge more metally, twangy closer to the neck more round and warm.
One of the most important things about the sound of a guitar is the back of the guitar believe it or not.
If it is tight against your body it will sound muffled.
If it is connected at two points, your thigh and say your ribs, the sound has a place to go to and the whole of the body can carry the sound.
It can then travel through your body and you your self become part of the acoustic medium!
The face of the guitar and the sound hole should be faced slightly up.
For two reasons: the sound can travel more freely and secondly you have more of an overview of what you are doing without having to creep your head forward.......thus compromising your body position, thus compromising the sound.....