Question number infinity! Would have you started and keeped going at Aikido if we didnt have ranks, colored belts, and the whatever else you recive for promotions? I know some dojos just stick to white then go to black while others go from white, to yellow, to next color to next color ect!
As I look back now at the very start of my aikido training ( 5 years goes by way to fast!) I may have not kept going at first without rank ( how old was I? 12-13 years old!) but now I wouldn't care as much becasue I love Aikido but its nice to see thoes shiny new blue belts! hmmm blue belts!!