I'd like to throw my hat in the ring and say: I think its shortsighted to attribute the decisions the characters made that we don't like to "intentional bad writing". Yes, both Candy and Meat were parodies of different kinds of bad fanfic that fail to understand the appeal of the Whole of homestuck, but also... every decision everyone made was in character.

Jane becoming a fascist and date rapist? She was literally raised as a corporate heiress. One of the first inner thoughts of hers we see is her planning to privatize the postal service. She tries to keep Jake as a sex slave when she's Crockertier, one of the few impulses during that mode that WEREN'T solely programmed in by the Condesce. And we see in the ending(s) that she revives CrockerCorp on Earth C, a clear demonstration that she has not grown out of her old ways.

Jade becoming a sex pest and a deadbeat mother? Think about it. She grew up without any physical affection accept from a dog, a dog she now Also Is. She isn't socialized, she doesn't know boundaries, she never even got those years with June during the timeskip because June had to retcon her presence there out! She's taking advantage of her god clout to be a party slut because she's desperate to make up for lost time but has no idea how to do so in a way that's healthy for her and others.

Dirk killing himself and/or going off to make SBURB happen again? He could never sit still, he always had to be in control, and now he's unable to cope with being in a slowburn coffee shop AU. He has to be in control, to make everything revolve around him, or he gets scared. Its also worth remembering that, via UltSelf mechanics, he's also Literally Lord English, which also influences those decisions.

I could go on, but I think you get the picture. The epilogues aren't as simple as "they're bad on purpose and that's why we don't like what the characters are doing". The characters are doing exactly what terminally online nerds from the 00's who got contracted into being child soldiers by the universe's ovaries, and then are told they're gods, would do. They're all maladjusted freaks. THAT'S why they act up.