If they're not convinced in Crytek's ability to deliver quality, they presumably want the option to switch developers like they did with Crackdown or Killer Instinct.That's odd considering MS have traditionally not been too concerned about owning IPs through third party relations. Maybe a change in stance since Mattrick left?
Given how much they would likely have to invest in Ryse 2, basically they want to ensure that they can still try and get money out of the brand if Crytek launches another 60 metacritic tier title.
Or, put another way, you can only demand owning your IP if your publisher thinks that your studio is high caliber enough that it's worth letting you have it in exchange for getting to be your publisher. Crytek is not the power player in this relationship and thus IP rights are not in their favor.