I've always just throught it's because the people who hate the Epilogues the most have more often that not haven't actually read it. They hear their friend (who also hasn't read it) prattle off a plot beat out of context and use that to burn down the whole thing.

I have my complaints with some of the content within the Epilogues but I can't exactly say that it's poorly written.

I will say that the writing decline from the Epilogues to HS2 is incredibly noticeable on a reread I did earlier this year, though.