Traps appear to be triggered when you pick the lock so are not if you just break the chest. Am I reading that correctly?
From a direct reading of the rules I agree with you. Only picking a lock triggers the trap (whether that happens on first attempt or when the lock is actually open is another matter).
However, you might houserule that some traps go of by smashing down the door as well.
But as a balance issue it seems fine that traps can only go of if you actually have a hero able to disarm them.