Every time I see discussion of a journaling file system, somebody implies they expect it to protect against corruption on power interruptions. I recall somebody who reported repeatedly turning his system on and off just to revel in watching it recover (without fsck) each time. It's not clear where people got the idea, but it's dead clear that people promoting journaling file systems have, again and again, utterly failed to make it clear that a journaling file system does not protect against corruption on power interruptions. (Crashes, usually. Power drops, often, but no promises.)
Pavel's complaint is a consequence of this failure.
I note in passing that there is no need, in general, for a file system that journals data as well as metadata to write the data twice. That's just a feature of common, naive designs. Journaling data along with metadata, howsoever sophisticated, doesn't protect against power drops either. Nothing does. Use battery backup if you care. A few seconds is enough if you can shut down the host fast enough.