Mostly, this particular case. In this case, it's a buzzword response that completely ignores any degree of nuance.

Any piece of machinery has a finite life. After a certain number of flight hours, you can't keep flying an aircraft safely. At that point, you have two options, you either: A) scrap the plane or B) repurpose it for something like this drone or C) conduct an absolutely massive overhaul program to inspect, repair, and lower/reset the flight hours limit.

The aircraft in the photo is an F-16A Block 15 ordered in 1983. Given the differences in performance between this aircraft and a modern F-16C Block 52, overhaul and retrofitting this aircraft isn't really worth it. If Option C doesn't make economic sense, you're left with Option A or B. Now, weapons testing, general R&D, and pilot proficiency are ongoing activities, so there's often a need to test something like a missile against an actual aircraft. This is where Option B comes in. You still get value out of destructive testing like this, in terms of performance data for whatever weapon you're testing.

I don't work in the defense industry at all, but have always had an interest in aviation. Also, aircraft development and evolution in general owes a lot to military use. A lot of what we use and take for granted today wouldn't have been developed without that driving need.