Do you play to improve or play to win or play just for fun?

Question kind of linked to lastshadow's recent video about winning low elo with simple champs and his tier list. Got me wondering how others think about this.
https://m.youtube.com/watch?v=h9ZWvmk1v1E Image version : http://i.imgur.com/k3FazYK.jpg Basically for low elo it seems to prioritise simple champions. Do you play harder champs to improve or have fun? Or do you just pick easy ones to win? What do you think of his concept? What changes would you make to that list?