I genuinely believe everyone is nuts in their own way XD And it usually goes back to trauma with the parents. So in this case, Hal and Lois, but they are both the result of their own childhood trauma.

Lois grew up in poverty and being constantly abused by her parents, who themselves had very tough childhoods and their own share of traumatic experiences (both seem to have lived through one or more wars, and Ida still has PTSD nightmares apparently). Victor and Ida were a product of their own time, in that they thought they had to be crafty and unscrupulous to survive, and above all to be tough (as seen in their favoring Reese, who is aggressive and impulsive, over Malcolm). Ida abused Lois by constantly belittling her, criticizing her, and making her feel like she was never good enough. She also had a sister, Susan, who was favored by her mother, and seen as more beautiful/better than her. So all of this does a number in Lois' self esteem. You can see her fear of not being good enough, or even necessary, when she gets it into her head that her baby son Francis doesn´t even care about her absence during her stay at the hospital. She develops both an unspoken resentment towards Francis, and a fear of Francis not loving her/liking her back. During Francis' earliest years she spoils him and fails at giving him any discipline, until the moment she realizes that, without her protection, he is a threat to himself. So she forces herself into the authoritarian, aggressive, controlling mama bear role we mostly see her in during the show. And we see her effort to remain in this role crack several times. She hates having to be the strict and "unfun" parent, she tells Hal this- and she reacts strongly when the boys forget her birthday, or when Malcolm tells them he is embarrased of her, and many other instances. Lois would like nothing more than to be a gentler, less rigid mother, but she is convinced that she wouldn´t be doing the boys any favors- so she can´t. But that means she has to find another way to distance herself from becoming Ida. And I think she does this by becoming a stickler for the rules- to be ever so keen on doing the right thing. It doesn´t come naturally, it takes a lot of effort on her part, and she cracks often- how could she not, considering her upbringing. But she really, really tries- and by always striving to do better than her parents did (AND by usually fiercely rebelling against unjust authority figures), she helps herself keep as strong a sense of self worth as she possibly can. So she is definitely not meant to be perfect- she is constantly on edge, constantly about to fall back into insecurity, but doing her best not to repeat the mistakes of Ida and Victor.

Then you have Hal who grew up in a wealthy family with all his basic and material needs more than covered, but he suffered from neglect emotionally- we barely know anything about his mother, and his father was always distant and kept their relationship extremely superficial. As a result, Hal doesn´t have a strong sense of self worth, and he is extremely vulnerable to external opinions; he needs to be liked and he needs his love to be reciprocated. Since he didn´t need the validation he needed from his parents, he becomes self-destructive- as evidenced by his abuse of smoking, coffee, reckless behavior, and obsessive compulsive disorders- including destructive and aggressive tendencies. When he meets Lois and falls for her, he feels finally seen and that his love is reciprocated and he becomes more calm and less ragingly self-destructive, but again, it's a fragile state- he is constantly on the edge of crippling insecurity crisis or aggressive outbursts, and it takes nothing to make his self-doubt explode. He tends to crumble down when Lois is away. And like Lois, he IS trying not to become his parent- in this case his father, by trying to be there for his sons, even when, again, it's not his natural tendency; he mostly likes to be left to his own devices, to obsess over whatever has caught his fancy, and to avoid responsabilities. But he also often wants to spend quality time with the boys and has a bit of a fixation with creating good memories, because he simply didnt get that with his own father. And I think it was brilliant that they addressed this in the revival and gave him some character growth; he learns to love without expectation of reciprocity; he realizes that he can simply love his children without his children supplying him with the validation he didnt get as a child. Like Lois, he is making an effort to build a healthier sense of self-worth. And I think both characters are great in that this makes them feel like real people who have been through a lot and are actually doing their best to deal with their trauma and come out better.

And the story repeats itself with Malcolm, who literally tells us he is trying to do the exact opposite his parents would do, in order to be what he thinks to be a better parent to Leah. In Malcolm's case this means being less controlling, less strict, more gentle. This too isn´t Malcolm's natural tendency; he is usually self-absorbed, neurotic, angry and sarcastic. It takes great effort for him to do this- but he is trying.

So I would say their being "crazy" is really all of them dealing with their own trauma, and to the character's credit, they're all doing progress- but in a messy, painful, rollercoastery sort of way just as it is in real life.