Removing small arms from the equation (50 cal and below in size) Minehunters and AORs. More crew, more complications, and removal from their main task.
AORs don't need weapons, they need more space for bullets and beans and every weapon on them takes multiple operators and techs away from the fighting warships IMHO. And tons of fuel/parts, while increasing costs.
Minesweepers don't need weapons, they need remote vehicles to detect, locate and eliminate mines. Every weapon on them takes away operators and techs from the fighting warships and removes space/weight to load and operate these vehicles/equipment.