I'm not sure this preserves the durability and accessibility difference you describe below, though. Suppose you have a hard disk instead of a magtape, and the hard disk's control mechanisms are kaput. Once you get through all of these, it should probably take a few lines of Perl.
Documents can be very difficult to extract, too.
The primary distinction is not whether something is imperative or declarative, but rather how complex and arcane the knowledge to decode it into a usable form is. The hardware is dead and emulaters only work for games. Depends on the information. But in general, I definitely agree with you. Use widely-understood data formats.