Infinite Achievements

Hey guys. Mos of us have completed the easier achievements in the game.Such as Gold Grab, Elixir Escapade, Friend In Need, Heroic Heist, Humiliator etc.Once we get to these achievements, we collect the gem reward and then, its over. You cannot replicate, redo, undo your achievement.So, for certain achievements, why can't the achievement reset and give us the chance to complete it again.Achievements such as getting to Crystal/Master/Champion or getting to 1250 trophies won't be reset.Also, the amount will be doubled from what it was first.E.g. For Humiliator lvl3, you have to destroy 2000 Town Halls.When you complete this achievement, you will get another one which asks you to destroy 4000 Town Halls.The gem reward would be the same.So basically, this is for the achievements that cannot be exploited.What is your opinion?