Villains do villainous things. I get where they're coming from, but Pennywise isn't supposed to be just some crazy clown that has almost no boundaries cause he got fed up with everything one day, even though he's human. Joker.

And even Joker would get the PC community upset by his antics in 2019. The new Joker movie already has people upset, and that's not even the "blowing up buildings with Harley Quinn in the passenger seat" Joker.
It's cool that the LGBT community is fighting for equality and acceptance, but this is a movie adaptation of a novel from the 80s... a horror novel. Things were way different back then and sure, they could change things up, but that could possibly change the entire story itself. And if Stephen King feels that it's important to keep in the films, then they're crucial -- he's the guy behind it all, after all.