Sometimes it's good to prevent passengers from seeing what's going on -- like when they drag the body of a deceased pilot out of the cockpit. I believe CO's 777 do have solid curtains between the front BusinessFirst cabin and the cockpit/galley area and so they were able to keep the pax from knowing what was happening.

That said, it's also somewhat difficult to compare privacy on a 777 to a 747, particularly because the 747 nose section (QF F) is inherently more private by design, regardless of what type of curtain you have.