Because they don't want to create a show for fans. They want to create a show to appeal to the TikTok generation and young'uns.
The writers and creators don't know how to treat these already existing franchises because they are creatively bankrupt and have to piggyback off a big industry name to get any traction. I am sure this show would've been fine for whatever audience they were targeting even without the name of Resident Evil attached to it. Instead, we're fed this high school teen drama/zombie apocalypse nonsense which has no love or reverence for the source material.
It's the fact that creatively, the people responsible for this drivel seemingly think they're above the source material. There's enough campy stuff in RE to make a fairly compelling, yet serious story.
but its from the same guy who did supernatural.