To understand the demand, we must first dissect the term. It is a compound of three distinct elements that, when combined, reveal a specific desire of the modern gamer.
No official cease & desist has been issued for Kamen Rider MUGEN characters, as Toei typically tolerates small-scale fan projects. Kamen Rider Mugen Android
A standard Kamen Rider fights Kaijin (monsters). A Mugen Android would likely fight a very different enemy: To understand the demand, we must first dissect the term