Reading the list of jazz, soul, and rock artists whose material was lost just made me shudder. If an example of cultural devastation is ever needed, this is it. Jazz greats from the 40s and 50s. Popular music from the birth of rock and roll to the modern day. This is truly a tragedy. Why wasn't this material protected in, at least, a fireproof area, or, better, in some salt cave in the Utah desert?
Because they don't actually care. No one in their right mind in these companies will sign off on releasing this stuff to somebody else. If some performance just happens to include someone famous and becomes worth any reasonable amount of money, the person who signed off will get fired.
The best way to preserve this stuff is to make copyright expire after 10-20 years. That way these companies can't just sit on these things indefinitely. They'll have to monetize it or someone else will likely come along and monetize it.