I've read numerous people write this online ("FromSoftware is just a bonus") but how do we know that? How much is their anime branch worth compared to FromSoft?
Now I don't find it because there are multiple threads about it in each forums.
But someone shared the Kadokawa revenue split: the majority of it was anime and specially manga/books/magazines, the gaming part was a minority. And out it, From Soft wasn't a huge part of their gaming revenue.
Regarding entertainment (games + movies + animation + music) Sony is now aiming to get way more IP from start to finish. Meaning, they want to not only to buy existing brands/IPs/content. But also to get the teams who make them to continue working them in the future and produce new one.
In the anime area, Kadokawa is one of the major producers not only of anime, but also of the manga and light novels where many of them come from. Sony already is important in the anime area, but acquiring them they would become the undisputed top 1 even more they are in gaming. And beyond this, it would also turn Sony the main player in Japan regard publishing of books / manga / magazines (Sony would now own things like Enterbrain or Famitsu).
In terms of revenue, that publication side of Kadokawa (manga, books, magazines) is the one that produces more revenue to them. They have way more businesses (anime, gaming, films, tv shows, music, etc) that are smaller parts of Kadokawa, but that would be more than welcomed in different divisions of Sony.
In case of gaming, to own FromSoft and Acquire (Tenchu, Way of the Samurai, No Heroes Allowed!, Octopath Traveller, Mario & Luigi: Brothership...) would be great for SIE. In terms of gaming history, Sony would also acquire ASCII, cocreator of the MSX standard where Sony started to make games and gaming hardware 40 years ago. But well, Sony already is a market leader in gaming and to get the Kadokawa stuff wouldn't almost change the gaming or console market.
TLDR: In terms of revenue the biggest chunk of Kadokawa is their manga and anime area, not gaming. And strategically, even if acquiring Kadokawa helps all Sony entertainment divisions, the most benefited one would be the anime side because would heavily change Sony's market's position and also Kadokawa's impact in the market because Sony's channels would help them reach a global market.