Change the loot penalty. Supercell please read.
When you get to town hall 9 or above, the upgrade costs suddenly become extremely high. And yet, there are many bases with a fair amount of resources - either they are too tough to penetrate, or they are lower levels which have little loots available because of the loot penalty.
So this is the dilemma. Higher town hall level people need a large amount of resources for their upgrades, but tough loot penalties and high match costs hinder the progress.