The 1st one could spice up the clan war scene a little bit like lets take a scenario (oh shit he has a diamond rank icon next to his name how you get it? "got it by clan waring") <-- that would motivate people to cw
or just use the prestige icons in DT
the codes are just sitting around in duel tourny and anyone could get it by just winning at least one dt
so might as well put it to better use