There are several reasons to max out. Foremost among them ties into the loot penalty. TH9's cant attack you at TH7 because the loot penalty is too great, they just won't get much loot. But when they see a th8 with the defenses of a th6, they go all giddy with joy. And, not only this, but it takes even Longer to max out th8, especially since almost everything can be upgraded twice. Troop upgrades and the other perks of th8 arent worth going up before maxing. Trust me ;)

