Why make an f/1.4 lens...

Alnitak wrote:

...if it's not going to be sharp at f/1.4?? Other than the 85mm f/1.4 (only had the D version), every other lens I've had, and all of the reviews I read, indicated that the lens needs to be stopped down to be sharp. E.g., "starts to sharpen up at f/2 and by f/4 it's sharp", or ..."OK results at f/1.4 but by f/5.6 it's sharp across the frame..."