Those are not my pictures. They come from GreenfireFarm's website, as did these:
I had just never heard anyone else mention the feathered shanks before, and was curious. Personally, I don't care either way, I just like the Sussex and am not a breeder. It so happens I hatched a couple like this (Coronation), and wondered what was going on. So, I investigated. Paul was kind enough to send me a message, and said:
The Coronations are in my consideration still a work in process. From my experience it is fairly common for them to have the lightly feathered shanks but still unacceptable. Some of mine (bred from Light Sussex) carried the gene over and have lightly feathered shanks and some of them do not.
I will continue to work with this breed, culling for the feathered shanks. I am not sure if the feathered gene is dominant or not.
It would be a through back from the Cochin ancestry. I believe there are three different genes that affect leg featheringing so it would be hard to breed out completely if recessive feathering genes were hiddened some in there.
What bothers me about his reply to you is the fact he says he culls for the feathering and doesn't use them for breeding but the OP says she bought the rooster as an adult so greenfire must not be opposed to selling birds with defects....if that is who she got her birds from.