Because there's only one story to tell, for adults, and it's the Jurassic Park (et al.) story.
You can't tell a period story for adults, with dinosaurs birthed normally and no modern science, because then it's not a 'talkie', and we're about a century past it being possible to have the budget for a state of the art dinosaur-prop film with no dialogue.
You can't tell a period story for adults, with dinosaurs birthed normally and no modern science, because then it's not a 'talkie', and we're about a century past it being possible to have the budget for a state of the art dinosaur-prop film with no dialogue.