But the thing is that Telltale's biggest selling point is their dialogue, plain and simple. Jurassic Park probably won't be as comedy-oriented as Sam and Max, but dialogue will still be a big focus. You want to hear what all the characters have to say, and since the playable character is the one you'll spend the most time around, you especially have to make sure he (or she) is interesting.
Sam has fun things to say. Strong Bad has fun things to say. Wallace has fun things to say. Guybrush Threepwood has fun things to say. Marty McFly has fun things to say. A Velociraptor...not so much.
The only way I can possibly even conceive it working is if there's another character around the dino at all times to fill in the dialogue void left by playing as a silent character. And I have a hard time thinking of somebody staying around a dinosaur so long without being eaten.