I don't really think they have to. With so many third party studios unable to fund/publish their own games now. I'm sure they are happy that MS offers to publish their titles.
Just like I'm sure Platinum was happy Nintendo payed for Bayonetta, and Capcom was happy Sony picked up the cost for SFV.
Shuhei Yoshida has said numerous times that majority of the 1st party games they make are not hits. Which is evident by how many studios they had in their PS2 heydays to now. While gamers appreciate the variety that Sony brought, they did not return the favor in kind by the lackluster sale numbers for a majority of their games, usually breaking even.
I think it's no big surprise that Sony embraced the Indie community to fill in for the dead areas between 1st party, and AAA 3rd party releases. while creating bigger buffer zones for major hits should a delay/ or unforeseen scenario develop. By keeping the community happy with time wasters and the occasional gems, everyone one wins. except for people that hate indie titles.
MS needs to play serious catch up with the indie community, hopefully some of this is alleviated with the impending integration of Windows 10 into the xbox 1.
Time will tell.