Nah, it's not lazy. It's literally the most common reason for Holy Magic use in Azeroth: Faith.
The Zandalari come from a religious society, where almost every troll worships some deity. You know what worship provides? Holy powers, by default.
It seems like just because you don't get it, you label it as lazy. Next thing you'll say that Zandalari warriors are lazy and boring because, to be a warrior, you need to be strong and train, and this is lazy.