History is filled with lost movies. A Page of Madness was lost for decades because of WWII, and a partial copy was found by pure luck. The original cut of Stalker was accidentally ruined during editing and Tarkovsky had to re-film the entire thing (and then did it a 3rd time because he didn't like the way it was shot the 2nd time. Absolute madman behavior). Some movies were destroyed by censors, destroyed because they were flops and the studios could reuse the film, or destroyed due to neglect.
Batgirl and Coyote vs. Acme are the first films I can think of that are lost because the CEO of the company didn't feel like releasing it. There's no way that taking the tax write off was a better move financially than just releasing the damn thing, especially with CvA apparently testing pretty well internally.