"Nobody goes there anymore. It's too crowded."
-- Yogi Berra
Writing is hard now, not because AI exists, but because there are so many writers out there and everyone's competing for attention, not just with other writers, nor with books from the past, but with all forms of media. Loads of people today, who might otherwise be reading novels for entertainment, are too busy scrolling their phones or watching TikToks or playing video games.
We don't have another Terry Pratchett because all the would-be Terry Pratchetts are toiling in obscurity, and possibly giving up on writing as a result.
Pratchett himself spent years as a journalist for a local newspaper before Colour of Magic.
These writing jobs in print media have mostly disappeared in the UK. It's certainly harder to make a living as a writer today than it was in the 70's and 80's.
There are some writers around who capture some (at least in the humour side) of the essence of what made Pratchett my favourite writer.
The Clovenhoof Series by Heide Goody and Iain Grant gets to Good Omens.