What follows is a purely hypothetical exercise, because, in all likelihood, no one will ever ask you "Why so much hatred for Charles Pratt?", mostly because they know innately that he is the worst, even if they are completely unfamiliar with All My Children or his previous work.
If, however, someone happened to ask you, "Why so much hatred for Charles Pratt?", you can pull out an annotated list detailing the reign of terror he has enacted which, by the time he gets fired (or the show gets canceled, whichever comes first), will rival Gone With the Wind in size, a list which can be updated today with the following piece of evidence to bolster your argument:
OMFG HE KILLED ADAM STUART CHANDLER
I am completely distressed by this, even though I knew that it was coming, and even though if I HAD to choose between Adam and Stuart, I would choose Adam, and even though Stuart appears roughly once a quarter so it's not like a gaping hole will be left on the canvas. If anything, that makes it even more distressing! The character has been on the show for 25 years, and is hardly ever on, so killing him off just seems to flipping the bird to the audience. "Oh, this character is beloved, and you'd rather him live peacefully off camera and occasionally interact with his son? That's cute. Hold that thought while I violently murder him."
He never fails to fail, does he?

While we are all accustomed to limitless horror coming from Pratt's poison pen, we are equally accustomed to David Canary being classy, awesome and a blend of the two, further exemplified by this interview with TV Guide.
AMC promised to kill off a beloved character and, for once, it isn’t an exaggeration. Stuart’s death is sure to upset a lot of viewers.
Well, I don’t want to be crass about it, but upsetting people is what they want to do. Killing Stuart gets attention. It certainly got my attention!
What will you miss most about playing Stuart?
I’ll tell you this: It’s going to be harder to win an Emmy! I’m embarrassed to admit it but I’ve won the Emmy five times, and every time I have submitted Stuart scenes. But I’m accepting this as a challenge. I think it’s going to help the show, and has the potential to be something very poignant, maybe even beautiful. Of course, we’ll see if having Adam solo is going to carry the weight the two of them did. I doubt that it will. But this does give us the chance to see another side of him—the broken-hearted man who feels he better get his life in order or else. This is going to put some real energy into the show. So, one way or the other, the spirit of Stuart will live on.
I absolutely adore him. I want to have drinks with him (in a non-randy way, because he is 45 years older than me*), and he can regale me with stories about AMC and Bonanza and whatever fascinating things he does in his spare time, because I am sure he is the type of person to have fascinating hobbies, and I will tell him, "You are just delightful, David Canary", because I would feel weird just calling him David.