Hank was a wife-beater in the comics? So what? Jimmy Olsen was a giant turtle boy in the comics, but that's ignored by the movies and TV.
I'm not so much concerned about continuity for the sake of continuity as I am about there being a rare opportunity here in comic book adaptation to show superheroes coping with personal demons that many people in the real world have to deal with. More people IRL have to cope with domestic abuse than have to cope with the fallout of having been turned into a giant turtle.
Yeah, I think it would make the character more interesting to not be afraid to embrace it. I'm saying this as someone who fully realizes that it's unfair to Ant-Man. It started as a simple panel where the direction was for Pym to just slap her. But the comicbook mantra of the time is don't do an action unless it's a big action, so that slap was drawn as knocking her completely off her feet.
Hank Pym wasn't the only one to slap a girlfriend in the comics. Matt Murdock has done it on occasion too (I want to say Heather Glenn, but I can't recall for certain). He somehow managed to avoid this label. So, if Hank Pym were a real person, I would say it was unfair to him. But he's not, he's a story character and, like it or not, other writers have chosen to explore this moment. I think that's a positive opportunity for more character development in the true Marvel fashion.
Peter Parker struck a Pregnant MJ, Cosmic Boy gave one of his female team members a backhander for asking him to use his powers on a religious holiday but nobody remembers or references these.