The use case for this is similar to the cold boot attack, e.g. disk is encrypted but memory is not. (And I don't know how encrypted DRAM works, but I wouldn't be surprised if some implementations put the key in SRAM that can be dumped using this technique.) Anyway, there may be valuable secrets that exist in SRAM but but not on disk.
https://en.wikipedia.org/wiki/Cold_boot_attack