It's a neat thought, but not one they should do on a handheld game. There's too much that can go wrong with something like that. Just like bomberman, where you can yell "bomb" to lay a bomb, doing so in a public place will not only make you look like a complete ass but would most likely get you inadvertently arrested for causing a panic. Likewise, saying some moves will garner you much unwanted negative attention in public.
And voice technology isn't even close to good even on things that need to use it. It would most likely end up being a feature that picks a move you didn't want to do on so many occasions you stop using it altogether. And something like that would very much ruin an online match because if you talk at all, for one your strategy is blown because your opponent can hear what you're trying to do, and if you accidentally call out an attack while just making conversation you'll run into all sorts of disconnection bullcrap. They're better off avoiding it.