It was a pain to understand that sneaking was the solution (because again, it makes no sense) and I had the same issue with the dead body.
Its one of possible solutions ...
Personaly i use fog mist or darkness ... its faster.

They don't help you about the statues, but the crown allows you to open the back gate from Nettie's sanctum, so you can walk through the backgate and reach the treasure without exposing yourself to the gauntlet of statue traps. Either way, you can lockpick most chests, so getting the key from the dead guy by the 3 statues is unnecessary anyways.
I know what it was for ...
But if you read whole topic, you might find out that there was sugestion of secondary use of that item ... so i provided secondary source.

Unecessarity is pure individual, and therefore kinda irellevant. :-/
Not all of us have rogue in our group (yes i know its uneffective, its not my fault that racist Githyanki can have only fighter companion) we can also be out of lockpics etc. etc.
Anyway, once there is option, it should be useable no matter how unnecessary it may seem.