Interesting. I've never seen any wheels turn green on them though. Ford definitely likes to change things though, just for the sake of changing things.
Those goofy 7-lug wheels actually stuck around for a while. They were an option on the '04+ F150s as part of a heavy duty package. Did you ever notice that the base model '99-'04 Super Duties had hubcaps with 7 "lugs"? They were used on 8-lug Econolines too for a number of years. Iirc, the hubcaps were first used on those non-SD '97+ F250s, hence the 7 lugs on the hubcaps.
I've got way too much useless Ford knowledge taking up space in my brain, lol.