Personally i love the long articles and pages upon pages of lore. It really gives you a greater depth to the world.
Personally i hate anime. I watched 1 anime, enjoyed it, tried to watch other and just felt sick to my stomach. It would bother a large portion of the community if the only way they could get lore was by watching weeb shit that we dont want to watch.
There is also the time investment. They can have a writing team make a 50 page lore book on the legal representation of Zaun in Piltover in the same time it would take them to make a 7min anime. And honestly..... i really want them to make a 50 page book on the legal representation of Zaun in Piltover... it would be amazing.
If you dont enjoy reading that is one thing, but for me and a lot of other people we love reading. Reading those pages upon pages of lore are incredible. you get to visualize the world in your own head. see the complex world as it is instead of someone elses representation. The zaun lore with the kids riding the elevator up to near piltover was an incredible piece. The intense visuals and the transformation from dirty Zaun up to beautiful piltover is something that just isnt feasible in an anime setting.
If they ever decide to do some anime type thing i really hope its 3 years down the line after they have fully flushed out the world with those wonderful endless pages of lore.
TLDR. I like to read. and anime is disgusting.