does hibernating really take as much power as a normal shutdown/reboot?
is hibernation more than saving used pages to flash (may be compressed), kernel init and reloading the pages from flash?

Granted, whether you can actually save power by hibernation compared to off-line mode depends on how long you don't need to use the device, but continuous discharging of the battery could also reduce battery life, correct?

However, for me the main purpose of hibernation is not necessarily to save power, but to be able to restore all application states after a period of power off.

Suppose your battery is low after a long day of intense use and you can only recharge it when you come back to your desk.
Now you have two options:

1) turn the device off and lose the session state (running applications) or

2) hibernate, and wake up as soon as it is connected to power again (or you have swapped the battery).

Don't you think that 2) would be a useful feature?