I hear this all the time from people who can't seem to adjust to using new programs. "X-Chat sucks", "Linux sucks", "KDE sucks", "Gnome sucks", "XP sucks", "Win 2K sucks"... Well, boo hoo. I'm not sure I agree X-Chat sucks just because you can't understand it.
But I agree that mIRC should have those features, even if it's only to maintain compatibility with other clients. My stance on this issue is that mIRC should use the UTF-8 encoding as the default encoding, and end the whole encoding issue for now. I think it would benefit IRC as a whole. As an added bonus, it would make it a lot easier to kick people babbling away in foreign languages on some channel, as you could just autodetect it based on Unicode range.
And IPv6 support is always a Good IdeaTM... Though it's not exactly the most urgently needed feature on the list.
Another feature I think would be reasonable to add, though, is the ability to join several servers and channels automatically every time you start the client. I understand this is currently only doable through a script.