they will stop making them when people stop buying them. Simple supply and demand.

Also, there's valid reasons why servos are mounted on the outside. You get better direct linkage with the servo located closer to the control surface. Short control rods won't flex as much. Almost every 3D plane is setup with this option. Mounting elevator and rudder servos on the exterior can also help with balance and reduce the amount of weight often added to get neutral CG.