Of course I do like the current voices of the original game. As skell said, I just think that some more variation could be welcomed. Just to make an example, L4D survivors are pretty popular in the videogame world because they are all unique, with their own stories (which sometimes they tell during a game) and their unique voice. If you put it in that way, KF characters are just random people with very few voices.
I just think that a right voice acting can add a lot of depth on the characters.
Another example.
Imagine a conversation between Sergeant Powers and Mike Noble
MN: So, how come you were able to survive so far this bloody mess?
SP: Coming home and finding that your family was reduced to giblets give you a good reason to kill all these bloody ******s.
MN: Fair enough. All that was left of my girlfriend was her partly-chewed legs. I can understand how you feel.
or maybe even more something like this
-Hey mate, do you really trust that Thorne guy?
-You mean Carnivore? Not a little bit. That freak gonna try to kill us soon, mark my words.
-At least he doesn't collect the zed's fingers...
-What do you mean?
-Don't you know? Powers has its own private collection of zed's fingers.
-...Do we have somebody normal in this group besides you and me?