If I have to guess ? Expand game pass and xbox and position itself as leader in the service / cloud gaming fishing for us suckers with cheap bait ... in the future with the market dominance stablished they can charge whatever it wants for gamepass acces .. as they do for windows , office and all the things they practically holds the monopoly ... is what they do is what they know how to do ... everyother market they have to compete or chase they fail ...
We can only imagine what plans MS had in mind with this and others aquisitions, we cant really know for sure only speculate and guess
One thing is for sure mate, keep giving quality AAA games for almost no cost at a regular basis is impossible even for a trillion dollar company, doom 4, sterfield, oblivion, all the COD , Halo, Gears, Forza ... put all together and is billions expended in development, you cant recover this money and grow practically "giving it away"
Free/cheap things are nice we all like them, but always be mindful of what you are bringing inside your home.
Anyway going to sleep, have a nice one mate.