Quoted from RayGun:I always liked BM 66. They did not, so off it went.
The network loved Batman66 TV series. It only went off air because of all the lawsuits and entanglements from all the major companies all claiming soul rights to it (DC Comics, 20th Century, ABC, Warner Bros, Greenway productions and Disney to name a few, lol) because it was so hugely successful. They tied it up in courts for many years.
Every actor in Hollywood wanted to do a cameo or appearance on it. It would have gone 10 seasons without all the lawsuits and is the very reason why it took so long to get it released on DVD.