I will be plain on this one.
Not wanted, not needed and pretty much pointless as far as I can see. I do understand the "pros" of having a voice chat inside the game, but it wouldn't really improve the game in any way, it would just make things worse for several reasons, and not all of these are really personal views.
First of it had to be created by someone aye? It would require quite some time getting it set up properly, and made correctly. This game needs changes and improvements as long as my eye can see and a voice chat would pretty much be one of the last things if not the last thing I'd want FH to implement. If time is going to be spent on adding content and changes to the game, wasting time on a voice chat would seem pretty out of place. If users want to voice chat so badly there's things like skype, teamspeak, ventrilo, mumble, xfire, steam even msn?
Counting away the time spent on making this function when it could be used on something more important, as mentioned above, you cannot really monitor voice chats within the game in any way.
And I really don't want to think about if the FH server would have to be the host of all the voice chat parties, I do not think this would be reliable, nor work in a good way. Game is probably enough for it at current date.
Personally I'd find FeralHeart downgrading itself if it added voice into the game, looses some charm.