I have to disagree. He grew up plain in sight standing the SW throne room next to Bolvar Fordragon and the scheming Lady Katrana Prestor who was responsible not only for his mother's death but also for his father's disapperance. So he saw things and he ventured out when Varian was back. Then the whole business with the Dark Iron dwarves, resurrecting his father, a student of Velen. They made him out to be stupid and naive which he can not possibly be given that he is also very smart.
Well, maybe you play Horde and haven't set foot into Stormwind castle from Vanilla through the end of BC.