I'm sure some work on the interface and how it looks wouldn't hurt and would probably be widely accepted. Adding support for other IM features (emoticons, video, etc) is where people start not liking the idea. There have been *many* threads on those particular topics and some have some very good points both for and against incorporating them into mIRC. In any case, Khaled has seen them and more threads won't sway him one way or another. He either plans to eventually implement them, or else he never plans to.
I will say that though I personally have no use for such features, I don't mind them if they are optional. As for emoticon support, there was a very good suggestion in one of those many threads that would actually be supported by many people even if they don't like the idea of emoticons. It's the ability to use a $replace-like command to replace given strings with images. This can be used for more than emoticons and would actually be very useful for scripters. It would also allow those who want emoticons to easily include them by setting up the $replace on ascii smileys to replace them with smiley images and because the images aren't built into mIRC, it would allow everyone to change out the smileys for new ones whenever they may want to. That idea is one that I would support fully... not for the smileys, but for the ability to insert other images as needed.
As a note on that suggestion, the ability to adjust the size of the image when replacing the text should be available. By default, it should automatically resize to match the font size, but there should be the ability to adjust it as needed. Also, the ability to use this in dialogs would also be useful, though probably more difficult to implement.