They absolutely will be and they have a place. In the Novel "Catalyst" they were being used alongside ISD I's at a battle being commanded by Moff Tarkin. He commanded one of them to bombard a cliff the rebels were using as a base causing the whole mountain to come down on top of the rebels.
I could easily see them being the Imperial version of the MC80 Command Cruiser. Give them red dice side arcs and they will pair nicely with The Arquintens Light cruiser.
Also note the that the ship has already appeared in rebels as a model behind Grand Admiral Thrawn's desk.