As some people said before, it would be nice to hear that it is part of your plan to create the DLC, which will give some mechanics, privileges and rights to powerful dukes and especially to members of council. As an example, you have great voting mechanic in CK2 (vote for/against declaring war or laws reform). Of course, that is small way to influence your liege, but pretty attractive. Or, for example, giving "grand duke" right to initiate a voting between council members to change some laws/individual duties, granting/taking titles of some vassals or choosing royal spouse (allusion of one russian empire chancellor (foreign affairs minister), who have chosen spouses for Catherine II grandchildren, because she ordered him to do so). Last variant is more possible when vassals get much control over their liege, I think...
P. S. - My sincerest regards - please, give us, finally, choice of coat of arms. I do not mean making separate update just for this, no. I mean you, possibly, can create button to open spreadsheet, where we can choose most preferable coat of arms from "pool". Sometimes I was full of anger, waiting for about 30 minutes to get desired eagle emblem. I also appreciate if you will do that separately from DLC with coat of arms editor/creation menu, so we could not wait that important feature for much longer time.
Oh, I just had that "Eurica" moment - you can give each council member his own right. For example, for finance advisor it would be right to steal some money from liege treasury in decisions menu. For diplomacy advisor - right to appoint/recommend spouses for his liege children or getting bonus alliance with one of his liege allies (in reality these advisors had to make long visits to royal courts of other realms to get good reputation for future parleys). For marshal - military buff and right to use kingdom forces if he has huge support of other people to usurpate the throne, because soldiers know him well. For intrigue advisor... here all is obvious enough - your liege can ignore your evil doings against others as long as you serve him loyally.
As my last word, I wanted to say thank you for paying attention to your audience and give my apologise to you for possible numerous mistakes in my speech, because I'm Russian, and rarely use Translate services for long and "thoughtful" monologues.