TL;DR: Plenty of modern fighter aircraft are equipped with arresting hooks, why not use them?
Poor runway conditions, i.e. debris, snow/ice, or even rain could be the cause to take a field arrestment. Partial runway availability is also a good reason, in case an aircraft makes an emergency landing due to battle damage or even just a failed engine. Depending ...
I can think of 4 reasons:
Pilot Training to use the cable arresting system
Rejected takeoff, fighters don't usually have reversers and may take long space to arrest
Under certain bad runway conditions, like ice, the required landing distance may be very high, and a military airport should work (ideally) under any weather condition
Runway partial ...
Found this definition on an FAA website today:
The runway touchdown zone is usually defined as 1000 feet from the runway threshold or 1/3 the total available landing distance. This provides runway “underrun” in case the pilot comes up short of his/her aim point, as well as increased obstacle clearance while on final approach.