I don't wanna spoilers for me
But i read about entangle. so if you cast entangle on enemy on highground, it will remove disadvantage from your archers on low ground, who attacking this enemy. Or give advantage if it just plain territory. So spell still works great and improve you chances by a lot (if we saying that disadvantage have big impact). So why it (or any other spells with advantages) call useless in game with height advantages?
I guess i can answer by myself, becuase people only talking about situations, when you already on highground, and there no point to cast this type of spells to get advantage (because you already have it). True, but in act1 you not always on highground. And plus as you said, you can be out of range, so no point to rush on roof in each fights, when you just cast spell. So again, spells fine as for me.