It has a cult following in the Philippines since they made their own English dub of it (which had the characters' names anglicized) long before Mighty Morphin' Power Rangers. Giving rise to homages like Kabayo Kids (kabayo meaning horse, and bayo is pronounced like bio) and Biokids.
And how about the cult following they have in France? It got to a point that, when Maskman and Liveman were ported there, they were respectively renamed Bioman 2 and Bioman 3!!! No wonder the idea of France Five worked out so well.
McLeaned: The death of Mika is a text-book example of this, due to the actress' sudden departure.
Real Life Writes the Plot: Yuki Yajima, the actress who played the first Yellow Four, left due to some shady circumstances that even today aren't quite clear. Some claim she had a falling out with J.A.C., the stuntworkers union that Sentai hired most of its early actors from, while fellow cast members believe she eloped with someone. Either way, the actress hasn't been heard from since then.
Haim Saban had made a pilot with the Bioman footage with original footage, but it was rejected by television networks. When he went to pitch the idea again in the 90's, he made a pilot with Zyuranger footage but kept the actor footage from the Bio-Man pilot.