Like I said, the disk is less likely to suffer corruption with EXT3. If the power is interrupted in the middle of a write with EXT2, you potentially have a corrupted file or directory. With a journaling filesystem, the data is first written to a journal area on the disk, then when the write is complete, they're moved to the filesystem. If the write fails to the filesystem, the journal records are still available for recovery.
It's up to you to determine if this is worthwhile to you.