I don't think they bought Activision for the games. Just for the cash flow. And specially king on mobile which is not talked that much.Even if they leave everything as is, they will make a crap ton of money
Their games aren't particularly exciting to me but can't deny they sell a lot.
Time will tell. They've talked a lot about Activision catalog IP, but it'll take intentional strategy to pair up strong IP with strong talent. I doubt the original creatives behind any classic Acti franchises exist as a coherent team.
As for Call of Duty's ongoing revenue stream, of course it is massive, but 69B is a massive acquisition cost. On its own, it will never pay off. The value is in exclusivity and keeping Xbox alive as a brand.
You could be right about King. I don't really know or care about their work. Maybe their revenue streams go further than I know to justify the 69B. But this whole acquisition saga would not have dragged out for over 2 years if MS was mainly interested in King.