I, too, have a long association with CDRs, starting in 1992 with a $30,000 Sony burner that lasted until just after the one year warranty expired and followed by a $17,000 Yamaha. I think discs were $25 each, and spoiling one was a serious business.
I bought a batch of CDRs from the biggest supplier on the Canadian west coast from 2002 to 2005 most of which will not play properly or at all anymore and in some cases are the only record of the masters. As you can imagine, this does not please clients who paid for archival recordings of important concerts - typically graduation recitals. This has really made me look askance at the medium, although my much older discs still play well.
My understanding is that hard drives need to be powered up regularly to be considered reliable and that drives immobile for, say, 5 years are at risk. I would feel more comfortable leaving reel to reel tape sitting for years than a hard drive.
Digital storage is not the sure thing it was presumed to be, even without considering changing digital formats. I am thinking very long term - like 100 to 300 years.
Maybe solid state memory is the answer, for all I know.