Your wish is granted in the sense that, if it were to become corrupted, it would be reversed. But since you're not really wishing for anything concrete, nothing happens anyway. Thus, it leaves you with a useless "wish" that doesn't do anything.
^Well that sure got dark fast. Alright, revamping this a little. Same wish, except that I own a house and property way out on the countryside for the dinosaurs to play in. And, while we do get visitors, it's nothing overwhelming. And nothing bad whatsoever happens to the dinosaurs (although I'm still fair game, I suppose).