I don't know any girl who would
pay for a female character in a video game. There's no real excuse for having Tripwire do new voices other than you wanting to feel pretty. Personally I'm comfortable playing games with a female or male protagonist, doesn't exactly matter much to me. Why should it to someone else?
Also to whoever said that foreigners would need to have a new voiceover.. hello? Pyro? Santa? Ignoring the fact there are two voices, we still have a guy/girl who shouldn't be intelligible at all, yet still speaks normally. Santa looks like he's in his 50s yet he still sounds young.
The voices and characters we have are fine. The only complaint I could possibly have is that the packs don't really seem to fit in with the others. For example, we've got soldiers like Lewis and Powers, but then there's yet another soldier we'd have to pay for, who's just more detailed?
tl;dr variety is fine, but I'd rather have Tripwire do more important things than release character packs.