Geez! Is the title "Metal Heroes" really THAT Hard to market? I mean that suits are badass enough for a 5 year old to want to buy the toys (at least for me and my friends it was)
Look at Ryuki, Faiz, Blade, Kabuto and Den-O.
Look at G3, Ixa, Accel etc.
They ARE Metal Heroes. They are just called "Kamen Rider".
In fact, if I am not mistaken, Ryuki was originally supposed to be a "real" Metal Hero show.
To be realistic, the Metal Hero franchise was kept on life-support during the 90's, and it started moving further and further away from the original universe that the Space Sheriff trilogy had created.
It already started to go downhill after Spielban. While Metalder became insanely popular with the older fan base, the show did not manage to appeal to the kiddies. Shows like Jiraya, Blue SWAT and Janperson had the same problem. They were marketed as kid-shows, but were aimed at an older audience.