Actually it is, I read somewhere that power draw in hibernation is only 5-15W on most computers as opposed to 200-250W+ on an idle system(can be far more if under load from heavy CPU/gfx card/hard disk use especially with today's PC's). Just touch a computer in hibernation or put your ear next to it, you wont hear anything and it will feel as cold as it would if it were off.
Power draw is extremely minimal.
I use it because I like to keep my PC off at night as my room gets pretty hot, and my PC is rather loud, but mainly so it'll wake me up in the morning(the scheduled task I have wakes my PC out of hibernation mode, but it can't turn on the PC for me if it's off).
It happened 3 times this morning, the last random shutoff was far apart(it was when I was typing this thread, fortunately Firefox was able to restore my session
). I'm gonna try keeping it on for a few days, hopefully that stress will reveal if the PSU is faulty, but it's damned hot over here.