support "quick" encrypt for new media (especially flash/SSD)
This mode simply applies the header and metadata, but since the container is empty, no encipherment is performed. The container is esentailly pre-filled with gibberish.
Once the OS starts to write (with a format first) it put the known data and the driver encypts only the writes and decrypts the future reads.
There is a single security risk with this approach, as the drive leaks the information about which portions have not had data written to it since the encryption was applied. This could be a risk for some usecases, but can be mitigated at any time by wiping the "free" space.
This would also require drivers to be written for OS installation.