Essentially what your monster system is doing is moving all your monsters. Movement is something that things other than monsters will want to do. My suggestion is that we can split this into mover component. This way we can make multiple types of mover components that subclass from mover (ex. AIMover, InputMover ..). Then we can implement a system than moves components that have an AIMover and a Spatial component. This will open the door up for more easily adding AI movement to any entity.
This something we should make a ticket out of to implement.