I'm a strong believer in fuses. I put one on each of my battery packs as close to a terminal as practical. The idea being that the fuse is there to protect the battery. If you monkey with your stuff enough, sooner or later you will inadvertantly wire something wrong and create a short and the fuse is the final safeguard to prevent a minor disaster turning into a major one. Even if you do everything perfect, a component failure in a controller or charger could lead to an excessively high current in or out of your battery and a fuse provides some level of protection for this.
Some protection schemes for devices such as power supplies or chargers utilize a diode that essentially becomes a dead short if connected to an improper load voltage. The diode prevents the more expensive electronics from seeing this voltage. A fuse in the circuit should prevent disaster.
As for motors and inductance, think of inductance as the inertia of a flow of current. Much like the flow of water has inertia. If you put your thumb over the end of a flowing hose the inertia of the water will spike the pressure resulting in a temporary higher velocity stream blasting out past the edge of your finger. It is difficult to abruptly and completely stop that flow, especially if the flow was large.
As current flows through a motor it creates a magnetic field. If the voltage driving that current falls then the magnetic field starts collapsing producing a voltage (similar to the water pressure surge of the above example) to keep the current flowing at the same rate. Motor controllers for ebike use should be designed to gracefully handle the induced voltage spike caused by the sudden loss of battery input voltage. This can happen not just due to a fuse, but also due to BMS overload protection or a wiring or connector failure. If a controller can't handle this, it would be better to add the appropriate snubbing to it or select a different controller. Eliminating a vital safety feature like a fuse to protect an inadequate controller is not prudent.
As for seeing a super current spike, this would not happen directly due to the induced voltage spike which only tends to keep the current flowing at the same rate. However if the induced voltage spike damages some component, much like a water pressure spike can burst a pipe, then that may result in a current spike.
