Nintendo has had quiet a few 3rd party working on games, it just not all games do materialize. But 35 third party games isn't that many, for E3 it is but if that all (which it isn't) that will be released in the next year it is. Also remember that not all developers can afford to have a booth at the convention, and everthing cannot be show in the limited time and space they are given. So what's coming out right now is the title we basically knew were coming out..
But yes I hope they don't spoil the surprises like the mystery Eternal Darkness title, though it may not surprise us at all.