to DarkStarX:
Well the way I thought of it is sorta customizable. You have a "smiley" config entry and a images/ folder. So you alt + o | Smiley then you click "Add" type

in the one box, then select images/smile.gif. So in theory, if the icons are too big/too small, you can either use a text editor and resize them, or just create new images entirely, or even just disable smiley support.
To The_Game:
well the smiley thing wouldn't really increase hd space. Looking at the smileys available here, they are about 250b each. That means you could have 100 smileys (which I'm sure most people will have far less) and it would only use about 2kb of extra space. But in any case, there are now 250GB hds available, even if it was a 500k increase, is that really a big deal?
As for video and voice, the voice chat feature available in kvirc is pretty small, I wouldn't think it would increase size at all really. Video, maybe it would, but again would a 200kb increase really be a good reason not to add it?