achivements and champion mastery

so, since everyone wants something special for reaching lvl 5 mastery , and the achivement system that riot implemented a long time ago, but was never used. why not make the lvl 5 mastery as an achivement, and for every lvl 5 mastery u get a special icon, a special champion skin that u choose for example, what about an extra rune page or two for reaching a high champion mastery points. I think that the champion mastery should be used more often and interract with other part of league.