To an extent, it depends on the game. Consider the two following games, if you will:
Riki-Oh: The Game of Ricky A game where you play the part of Ricky.
Doing Time: Surviving in a Privatized Prison A game where you create your own character.
The developer had best not give my character a voice, because they will never get it right. By not giving my character a voice, but giving NPCs a voice - you can end up with some of the silliness seen in The Secret World. Still, I prefer that silliness by leaps and bounds to the outright nonsense as seen in The Old Republic.
In adding voice, you also have to consider how you are going to present text as well. People that play without sound, deaf players, or even those that are visual rather than aural…will want text as well. Of course, you’d also have to make it so the folks that do not want to see the text, do not see it either. Hell, to be blunt, you’d have to set the voice on it’s own volume channel or present players with the options to disable it if they did not want it interfering with their reading of the text.
Another item to consider is how you are planning on adding it. Will it just be random NPCs talking? Are you talking about cutscenes? Will there be options to disable that? What kind of replay thing are you going to have? Each time you talk to the NPC, do you have to listen to the whole thing again? Can you kill that NPC to shut them up?
There is little doubt that there are those that crave voice in their games. I generally ask them the same thing - hey, it’s like when you read a book and then go see the movie…how weak that movie feels compared to the book, am I right? The usual reply is…there’s a book?
So yeah…different folks will want different things. Consider your market - are you making a game for X people, Y people, Z people, or some sort of thing to attract X, Y, Z?
Personally, I can’t remember a game where I did not take issue in some form with voice in it. It’s kind of funny, because if some of them were to get together and use the various parts…it might not have been that bad. But, it tends to be just that bad…meh.
edit: btw, you can watch Riki-Oh: The Story of Ricky over on Crackle…