App Concept: Games With Voice Input

Several new apps featuring voice input have been popping up in the App Store recently. Dragon Dictation is one such example, allowing the user to speak their texts or emails instead of bothering to write them. The same goes with Google and Bing apps that enable voice search.
So for the life of me I can’t understand why I haven’t seen any games (such as trivia games) integrate this into their apps yet. In theory it seems like it would be easy enough. Let’s say, for instance, you are writing a trivia game for the iPhone that uses answers besides multiple choice. It seems as though the only way to input answers right now is to use the keyboard and type it out, which would take too long and cause the game to go much slower. But wouldn’t it be much nicer and easier to just speak the answers as if you’re playing a live game show?
My only guess is that it’s harder to come up with this feature than meets the eye. Perhaps the problem lies in producing a certain API that a developer can use to enable smart voice input, much like Dragon. But once somebody develops an API for it, I assume it would be a huge moneymaker for them as they sell it to countless devs out there wanting to integrate that feature into every type of app imaginable.
Let me hear your thoughts on this. Am I off my rocker, or is this a legitimate concept that would add yet another level of sophistication to the iPhone user experience?