In any standard Windows GUI, right clicking on a menu item inside a right click menu causes that menu item to be activated.
I think it would probably take some substantial amount of work to override that behavior. And even if they could do it, I don't think they should. Breaking standards is a no-no. You could end up with new users not even knowing the feature was there, and people (like me) who instinctively click on a right click menu item with the right mouse button. I started the action with the right mouse button, I intend to finish it with that button.
Some sort of customization screen for the menu would be nice, but again, you're looking at some substantial amount of work to incorporate that.
I have a feeling we won't be seeing anything like that anytime soon. Probably not even in 9.1 or even 10. But who knows? MJ8's MEGA-ME skinning was a big suprise, and a real late addition. It would be nice, though, if we could completely customize the menu.
For now, I would be happy if the number of sticky items would grow to about 4. Even happier if its behavior was changed slightly to keep the Most Used items at the top instead of the Most RECENTLY Used.
Most Recently Used changes so frequently that it's quicker to assume that the item you're looking for isn't there, than it is to first check and see. Most Used would change more slowly, and would actually adapt more to your individual usage.