No.
First - voices naturally limit things. With a voice, the character is no longer who you imagine, but becomes the voice. You're no longer free to imagine who and what the character is, but are locked into the devs' notion of who and what s/he is.
Second, and much more importantly, voices take up time, budget and memory. If voices are included in a game, they're included IN PLACE OF something else. Everything is finite - there's only a certain amount of time, a certain amount of money and a certain amount of memory available to the game. There are MANY things that are more important to Pokemon games than voices could ever be, but if voices are included, it's just about guaranteed that at least some of those things would be limited or even cut entirely, simply to make room for something the games really don't need anyway.