Unlike other suggestions, voice/video chat is chat related. It certainly has more of a place in mIRC than does for example, mp3 support, or numerous other things mIRC supports. In fact there is already a client called KVIRC that already supports DCC VOICE. I really see no reason why this shouldn't be added to mIRC. It'd be a very nice thing, a DCC CHAT except instead of text, you can actually hear the people you are talking to.
Umm it is supported I am almost done with the server bugs and I will release it soon on mircscripts.org. Check out the screenshot section on the Site and look for [mIRC] Voice Chat