Presumably, she isn't party to an emolument clause and that means having unprecedented access to most sensitive economic and political information will give her immense opportunities to make substantial amounts of money from her future business dealings.
Normally anyone that close to the President also rids themselves of conflicts of interest. There is no indication at all that Ivanka plans to do that--or even that Trump has actually followed through with doing that.
I would bet they are doing this because the admin is so corrupt and incompetent they felt the need to protect her by granting jet officially the clearance to hear things that will get most of them in trouble once Trump is impeached.
It's also important to note that while FLOTUS tends to have a role and Ivanka is allegedly filling such a role, the Office of the First Lady is in the East Wing of the White House. The West Wing is traditionally (and exclusively) close advisers and people who work directly for the President. This is an unorthodox move. I imagine it's because they cannot legally make her a salaried adviser to the President without violating Nepotism laws.
Republicans will never elect a woman. Not as it stands right now. A lot of Republicans (especially Evangelicals) would rather abstain from voting than give a woman the highest office in the land. Also, I don't think Ivanka is actually a Republican at heart. She may be going along with her father for personal benefit but reports point to her and Jared being a lot more moderate than Trump/Bannon.