IT could be so much scarier than it is/was. It's about an alien/demon which manifests as what you fear the most. The fears that Stephen King tapped into in the 1980s were pretty basic as far as fears go. I mean, I guess Mike's fears around racism could have been scarier, but the scariest part of that was when the jazz club was boarded and burned, and that was back story. Bev's fear was getting her period, hence the rush of blood from the sink (and her father's odd behaviour, wanting to 'examine' her). Then there was the bullying.

Welcome to Derry is set in the 1960s, about a decade after the book, and doesn't do that much more. In fact it throws the book canon out and makes its own, borrowing some from the book (such as the jazz club).

They could take it to modern times, and get into some really scary shit that some people have come up with. Technically Alien could be an IT movie, if the aliens were just IT. Because what's your greatest fear if you're exploring some old derelict space station? Being trapped there, hunted by aliens that drool acid? Yeah, that'd be up there. Anyway, I feel like they could come up with some shit that would stick with you more. The first season was okay, but it was more Stranger Things than IT.