Checksumming isn't enough to make something a good archival format. You need to go beyond being able to detect data corruption to being able to correct or cope with data corruption. For a FLAC file, if you flip a bit in the file, then the checksum will detect that the file has been corrupted, but that chunk of the file will be unrecoverable. If you flip a bit in PCM data, likely you won't even hear the difference. If you want to know whether corruption has occurred, you can always run md5sum on it. For FLAC, if you want to be able to cope with data corruption, you'll need to create something like par2 recovery data.