It is inevitable that those old J6 drones are being phased out due to high logistic costs, maintenance costs and operational costs.
You will need to have big physical spaces to store them, depriving other drones/aircraft from using these spaces at the air base. Then you have to keep inventory for replacement parts which are no longer in production, and you have to keep teams of ground crew who you can better deployed for latest aircraft in service, and so on.
New suicide drones are much smaller, use far less fuel, minimum maintenance, minimum ground crew requirment, no time consuming pre-flight checks/preparation like fueling, battery charging, oil check, checking functioning moving mechanical parts and so on.