This is a very controversial topic. So I must clarify that this is just my opinion and you are welcome to disagree. As an Xbox owner I do not believe that these acquisitions have or will benefit Xbox owners at all. Let me explain why, Bethesda and Activision games would have still released on the Xbox regardless. The only difference is now it will (potentially) NOT release on the Sony platforms. And I understand the logic behind this from a business' perspective, it will definitely help Microsoft out. But my problem with the whole thing is, how will gamers benefit. Sony is definitely guilty of this too, they secured Street Fighter and Final Fantasy remake for the Sony platforms. However, one must point out that they have organically created new IPs from their first party studios , games such as Last of Us, Uncharted, God of War, Spider Man, Ghost of Tsushima. Microsoft has not done so since the Xbox 360 days. My fear is that this policy of just acquiring existing IPs is going to be the norm for them, this will discourage any creativity or desire to start new IPs.
I have tried to make this argument on Twitter and Reddit, but people have labeled me as a "salty" Sony fanboy. Even respected journalists are enthusiastic over these acquisitions. I personally do not care for Sony or Microsoft, I just want new ideas and new games because that in the end is what's good for all gaming.
And here I was thinking that Microsoft funded and published Sea of Thieves, Grounded, Ori, As Dusk Falls, Tell me Why, Ryse, Quantum Break, ReCore, and Sunset Overdrive; and it will soon publish Pentiment, Everwild, Contraband and Avowed. Silly me, seeing these investments the only logical conclusion is that Microsoft is not interested in new IPs.
And I can totally see your concerns about creativity, I mean, look at how similar Pentiment, As Dusk Falls, Gear Tactics and Sea of Thieves all look and play. They are certainly lacking that "3rd Person Action Adventure" flavor that is so synonym of creativity and innovation these days.
Oh, and I'm still trying to figure out how Spiderman is more of a "new IP" than Indiana Jones.