This acquisition is good for Xbox fans in several ways that don't depend on exclusivity, people need to stop with this nonsense that Xbox fans are happy because Playstation fans won't be able to play these games. Sure some of them are, but a similar proportion of Playstation fans cheer on exclusives too and it's better not to interact with those types of people on all sides.
1. This acquisition will bring many great games to Game Pass, past, present, and future.
2. This acquisition will be big in increasing Xbox's comparative market share, (won't pass or even catch up to Playstation obviously, but it will improve) meaning it will be harder for devs to avoid making Xbox games, and make it more expensive for Sony to buy exclusives (Yes Microsoft does this too and I don't like that, but objectively there will be less games missing Xbox which is good for Xbox gamers)
3. This acquisition may help getting some Activision published Xbox/360 games into the backwards compatible program, which is more games for Xbox gamers
4. This acquisition could potentially lead to revitalizations of series like Guitar Hero, Tony Hawk, or other various popular Activision franchises (not saying this is super likely, but more likely than the basically 0% chance they currently have, Game Pass makes it easier to make small-mid size games and see if they can work)
5. For PC players this will lead to every Activision game coming to Steam
6. This will allow every Activision game to be able to be streamed and played on basically any device
The majority of Xbox fans are way more excited about things like the above rather than the games being exclusive. It will result in more games for Xbox gamers, and more games in Game Pass. I completely understand people who don't have Xbox's being mad about games potentially becoming exclusive, I would be in reverse too, and maybe I'm too optimistic about the state of humanity, but I don't think the people happy about this acquisition are happy that Playstation fans may lose access to the games, they're happy about the benefits they would get from the acquisition