This is one the fans having been asking us about demanding for a bit. Black Ops 2 has an option to "Install Textures to HDD."
When we explained to PS3 folks that installing to the HDD wouldn't neccessarily give us any significant performance gains, they explained back that the issue is they play so much it puts constant stress on the Blu-ray drive and wears them out.
It's a non-trivial amount of HDD space to install all the textures. I don't want to get into exactly numbers because anything can, and does change during development.
You don't have to install to enjoy the game. We still pre-cache like we did on Black Ops.
David 'Vahn' Vonderhaar