Now, when I say ‘characters you hate’, I don’t mean villains.
In fact, some of my favorite characters in pieces I’ve written and read have been villains.
What I mean when I say ‘characters you hate’, is the characters who are reprehensible pieces of crap who also (unfortunately) serve a significant purpose to the storyline.
It’s not easy to write them. That’s established.
Writing them is tedious and boring, especially when you have characters you love to write and love to make scenes for, but if you don’t also spare time for the bad ones, then your story has a significant hole that needs to be filled.
It’s hard to craft a well-rounded story when you’ve got say, 10 characters that you love to write, because you put the most effort into making those characters perfect.