I don't blame the OP or anyone else for wondering about this issue. I would expect any modern connected device to be able to set the date and time automatically, because why not? It has access to plenty of information on the web that can tell it what the correct time is. Granted, Android devices that don't have a cellular radio can't figure out the time zone automatically, but they should still be able to determine GMT easily (and then the user sets the time zone manually).
It's also not that unusual for a tablet to run out of battery from time to time. I don't use my 10" Transformer TF300 every day, because it isn't my daily driver, so sometimes it shuts off automatically when it reaches the low battery state. I agree that it would be a hassle to have to manually reset the time whenever this happens. Sure, it's not the end of the world, but the question here is why would they even design it that way?