I never got a sense of the “bad parents” thing.
It’s not phrased like that in the movie, but the muscle in the First Order is Han and Leia’s son, who went to the dark side. And Han and Leia question themselves over why it happened.
And it’s also said by Solo that the reason the supreme ruler or whatever wants him is for his power.
I find it very over the top and not entirely serious to have a plot which hinges on the premise that Han and Leia could’ve done simply something, or many things differently with their son, but that now the whole galaxy is experiencing a total reboot of the same threat as in Episode IV.
Realism is a bad thing in a sci-fi fantasy movie, I guess?
Marriages fall apart because of something that happens or doesn’t happen with a child. I found it interesting to put that in a Star Wars movie.
There’s a deleted scene in Aliens (reinserted in the SE) that explains how Ripley lost her daughter and it’s what drove her caring for Newt. I loved that.
I also loved Sandra Bullock’s backstory in Gravity, and even some of the backstory in The Babadook.
But different life experiences bring different viewpoints. My viewpoint is shaped by my experiences.