Hiya,
If you could do this you truely would be making MJ thousands of times faster, more user friendly and faster at doing every day tasks.
I'm not sure if you've ever tried Topstyle Pro but in v3, and if I remember correctly, also in v2, it has an option on the right click Menu to: 'Customize Editor Menu'
This allows the right click menu to be totally modified to our own preferances.
Something like this, even if not quite so dynamic, maybe requiring us to specify details in an option screen, would allow us to totally configure MJ how we wanted it to give us a LOT of speed and quick access to features we use and allow us to hide away features we rarely use.
Also, along the same lines, again just BEGGING for the 'Send To' playlist menu to be cascading in the same manner that the menu's are set in MJ itself. My list fills the page and requires a LOT of scrolling to find playlists. Basically rendering it useless.
Also, could 'last used playlist' that gets saved at the top be configureable so we can say how many 'last used' items we want it to show as in XP.