[Miki1988]

It would have made no sense keeping the White Ranger powers since the writers made Zordon have the monologue about "the Power Rangers how we knew them are completely gone" in "A Zeo Beginning, Part II". Besides, the Kibaranger suit wouldn't go well with the Ohranger suits. Saban got lucky with Kibarager since the shield kind of resembled the Green Ranger one along with some suit elements that blended well with the elements from the Zyuranger suits for MMPR.

Another problem would be - like Titanium Ghost said - adding new footage would be too much work, the ratings were going down and the Saban needed to save cash in order to maintain the show and the franchise. Plus there's a possibility that Tommy would be a Zord-less Ranger since Ninjor was back at the Ninja Temple and the Ninjazord/Shougnzord technology wouldn't work with the Zeo tech unless Saban asked Toei for a Ohranger2 footage which would feature at least Kakuranger and Ohranger mecha be somehow compatible, combining-wise. For which - I don't believe - Saban had the finances for at the time of production & filming of Zeo. It's why Saban had Jason come back as Gold Ranger which boosted the ratings, which made Power Rangers be able to last to trough Turbo which was a ratings flop which led up to Power Rangers In Space, the season that brought some of the old audience back and perhaps even attracted some new audience which was enough strong power boost the franchise needed to survive.