[windward]

Non-verbal creatures don't make very good antagonists on their own. Jurassic Park's premise makes it a story about human folly, but the time travel setup would make them a distraction from a moral quandary that we're already very accustomed to.

On the other hand, zombie movies get a lot of this for free. Hell is full, there is no rest, humans are the real bastards.

[mitthrowaway2]

That's a good point. But as they say, the three genres of literary conflict are "man vs man", "man vs nature", and "man vs himself". There are many good films that don't have a human antagonist, such as Cast Away, and there's no reason Wilson couldn't be a dinosaur. =)