The thing was the original idea was to have a single hero adaptation of Metalder... with Jason David Frank as Adam Steele/Cybortron (this was between the fade of the Green Ranger powers and the surge of the White Ranger). Hell, there's a pilot about it around, and the transformation sequence is actually more complete than Ryan's, using all the complete footage of the transformation.
The reason it didn't got made, believe it or not, was copyright: Cybortron... doesn't seem a lot like Cybertron? As in, the planet from Transformers? Yup, Hasbro sued Saban about the use of Cybortron as the name of the series and the character (before you ask Cybertron was indeed a character... a transformer planet whose original name is Primus and is the nemesis of Unicron), so they scrapped it. Also, JDF actually became very popular as the 6th ranger, so they had him return for the appearance of the White Ranger.