I gather that Jetman
was one of the series that Saban considered for adaptation into MMPR. Starting out with a more tech-based season might've made MMPR turn out differently, and if nothing else it would've been fitting because it already had two female team members. But I guess I can see why they didn't go for it. There was too much conflict and solemnity among the villains, not to mention the cigarette-smoking robot, so that footage wouldn't have been as usable. Also the villains directly confronted the heroes rather often, and there were a lot of scenes of the Jetmen out of costume in the Icarus cockpit.
And I guess the mecha was cooler in Zyuranger
. The dinosaur/extinct animal machines were more visually interesting, and probably made better toys, than just a bunch of different jets. Being the first Sentai with a recurring sixth Ranger also provided more interest/merchandising possibilities.