Jump lists have been suggested before and there's a small potential in mIRC for them, mainly only through scripts. Transparency support might be added at some point.
As far as ribbon support, you're right... people will complain. Myself included unless it's completely optional. You'll find a lot of people that hide the menu bar itself... people don't like a lot of vertical real estate taken up by programs. Ribbons take up a 4x or more vertical space as a menu bar does. If replacing button bars, it can be less depending on the number of bars you have, but mIRC really doesn't have many buttons or even very many menu options and only one button bar and one menu... you'd at lease double the height of it. No thanks. Also, ribbons aren't necessarily any easier to use. For the most common things, it can be useful because they are placed right in front of you. But for anything that's not commonly used, they get pushed back into "hidden" places that aren't as easy or quick to get to as a menu.
Buttons - About 15-20 (don't have it in front of me to count)
Menu items in default install - Maybe 20-30
That's not enough to really make a difference in adding ribbons. Just because ribbons are new and flashy doesn't mean they are better.
