Factory produced optical media is basically "stamped" or pressed (injection molded) unlike writable optical media that have to be burned individually.
So a disk factory can crank out tons of disks pretty much faster than any other means of hard data replication once the glass masters are set up and the assembly line is ready to go.
Essentially, flash memory will never become cheaper to produce than optical media, which to software distribution companies is ultimately the bottom line. So unless flash storage provided a magical way of stopping game data copying/piracy, publishers have little reason to use it for full sized games, even as the price of solid state storage continues to drop because it still won't drop faster or lower than optical media.
Availability of larger flash storage capacities is irrelevant. What matters is cost effectiveness.







