Police & Taxi struts are quick and easy, if the struts you have are in a state of ruin, ... and your plan is to do them yourself.
The complete strut saves TIME and potentially dangerous work.
The old ones just get dropped and a whole new strut goes on. The vehicle's back in action without messing around compressing springs.
The down-side is you can't pick and choose dampers.
You live with an often unadjustable, harsh riding, heavy duty shock made with durability featured rather than comfort.