Why should they expect a lower return? While I understand that value in being unique, I can't imagine a high quality production of a public work would be damage

Why should they expect a lower return? While I understand that value in being unique, I can't imagine a high quality production of a public work would be damaged that much by low quality productions of a similar work unless it's just profanely overdone. And in that case, why would they have sunk that much money into it? I mean, every time a zombie film comes out, three cheaper ones come straight to video. The new Dawn of the Dead did fine. And even in copyright, Snakes on a Train was in video stores three days before Snakes on a Plane came to theaters! Sure, they may have had to think of a unique name to identify their product to fans (even just "Peter Jackson's LotR",) but I'm not convinced that they would've suffered, had lower quality renditions been widely available. It may have made them stand out more.