[Goldar's Revenge]

They also needed to do it to make the Kakuranger footage work. It was getting harder to work around. Its funny because the Ninja Zords were released second in Sentai. PR flipped it. The Battle Borgs were also around before the Shogun counterpart. So it makes sense why they were stuck using the morphed Sentai footage. They could have had the regular Rangers just change costumes. But as Zabitan says it was likely because the actors wanted a break. They did much longer seasons back then and the schedule could be grueling.