>>1525682>I wonder why I don't see people doing that?Because most of the time people lay on a hammock diagonally and not straight. Laying straight puts more stress on your back and especially the backs of you knees because they are constantly over extended.
Diagonal lay enables you to have a more even surface and many hammocks are cut in a way it's really not even possible to lay in them straight.
Also if you have a permanent bugnet on your hammock, using a sleeping bag like you described is impossible.
They do however desing mummybags for hammocks also and they are used just as you described, but they are very rare.