KenV is not quite correct.
Note that the g requirement is not "sustained" in the normal US-standard sense in that height and speed may bleed off. So it's not about air-combat training but about assessing the student's response to elevated g (and rapid onset, since the maneuver starts in straight and level flight).
http://www.avia-it.com/act/areariser...ntensifies.pdf
Because you really don't want to find out that Lt Scroggins can't do a g-straining maneuver worth a damn when he's solo in a $150m jet.