Because the eye of the jailer is nothing but the eye of Odyn that Odyn gave away because he was tricked by Mueh’zala and that is one of the Jailers greatest assests so we want to get rid of it so or so. Which we do by fighting it in the sanctum of domination. Makes no sense to have it active in the maw when we have literally reduced it to metal scraps within the raid.
Also threatening is highly up for debate depending on class. The eye is nothing but a stygia block for me and not a threat whatsoever.