The first item is software - not related to storage device (except for recording length)
Item 3 and 4 have to do with the CVR\FDR it self, not the storage device. (I have never seen a PCB that can withstand anywhere near 1100C).
All those requirements relate to the "crash-survivable memory unit", which is basically a tough metal container filled with an insulating material and the solid-state memory chips.
However, you're absolutely right to say that the storage capacity could easily be increased. Indeed, these units come off the shelf with 512KB of ROM memory but can be expanded with optional flash memory.