I think the appeal of this is that it won't be easily killed by snubs like battleships are now and it will make battleships usable.
My ideas to improve the concept are: Only one for each house. Outcasts and corsairs making efforts to build one.
Make them huge like barges with the same maneuvrability. Can only move through systems by jumping.
Not indestructible, just huge armor: 10x a dread.
This links to my thread about bombers. So if you nerf snacs or buff battleships you will make battleships usable.
I think there is a place for such a class of ship in the mod. But like i said they should be unique to each house and only one. Let the ship designers jump at the opportunity.