The problem with Mrs. Bennet is not that she wants her daughters married well. It’s that the specific way she goes about it is damaging to the girls and to their prospects, and also that while she goes about complaining about what’s to become of them in the future she’s making their lives much worse in the present.
She plays favorites. The girls she likes (Lydia, Jane) can do no wrong. Lydia, especially, has never had a boundary in her life that she couldn’t whine her way out of. She is spoiled, selfish, and utterly unprepared to face the larger world. Instead of being treated as the adolescent she is, she’s treated as both a child who can’t possibly take responsibility, and also as an adult capable of adult judgment. She’s given no guidance at all beyond “go have fun!” and it leads directly to her marrying Wickham. They’re going to be poor, he’s not going to treat her well, she’s probably going to have a miserable life. Directly as a result of the way Mrs. Bennet treated her.
The other three girls sometimes get treated well, and sometimes get treated badly, depending on her whims. You think that hasn’t left scars on their psyches? Especially with Mr. Bennet tearing them down constantly? (He doesn’t tear down Elizabeth, his favorite, very often; but he also doesn’t see her very much as her own person or understand her. And she has to know, even if unconsciously, that he could treat her as badly as he treats her younger sisters, if she seriously displeased him.)
And the thing is, what she wants most is for them to be married. Not happily married, not even well married, just married. Sure, ideally they’d marry rich men; but when the militia comes to town, she encourages her daughters to flirt with the officers. The militia is full of men who are technically gentlemen but don’t have enough money to support a family. That’s why they’re in the militia! They don’t have land, they don’t have a profession, they don’t have enough connections to get into the regular army. They don’t have enough to support a family now, and they probably never will in the future. But oh, yes, flirt with the officers, go to Brighton and find a husband in a militia camp!
The other thing is, Austen knows very well that even if your material needs are taken care of, being married to the wrong man can make life a misery. There is a reason her heroes tend to be stodgy, slightly older men whom the heroine already knows. It’s because such men are SAFE! Their characters are set, and they are not going to turn out to be abusive. The exception is Darcy, and it’s Elizabeth going to Pemberly and seeing how well his servants and sister are treated (nobody’s being abused, everyone is happy and well-cared for) that is the turning point in her falling in love with him.
Mrs. Bennet does not know this. She does not give a flying fig for what kind of man her daughters marry. Money? A red coat (and therefore a dash of romance)? Either is good. All she cares about is that the ring gets on their fingers. No other considerations apply.
And do you think the Bingley sisters and Mr. Darcy are the only people who have seen Mrs. Bennet and gone “ew, gross, she’s crass, she uses incredibly transparent moves to force her daughters into closer acquaintance with possible suitors, and she’s a terrible mother whose younger daughters are badly behaved because of it. I don’t want any connection with her, even if the two oldest are okay by themselves.” I really, highly doubt it.
So there is a lot to legitimately criticize about her. It’s just ... she’s not very smart and she’s probably doing the best she can. Mr. Bennet is very smart and doing the absolute least that he can. It makes a difference.
Mr. Bennet claims to be so perceptive, and yet, in the end, he doesn’t see Elizabeth at all.
Things he could have done that would have materially made his family’s lives better:
1. Saved money for their dowries. This would have both made them more likely to marry AND given them more money to live on if they didn’t marry.
2. Encouraged and rewarded good behavior, instead of ignoring and mocking them by turns. He does this a little for Jane and Elizabeth, why couldn’t he have done it for the younger three? (Note that even Jane and Elizabeth get dissed sometimes.)
3. Ensured they had decent education in the sort of womanly arts that were considered essential on the marriage market: music, art, modern languages, etc. They could learn if they wanted to! ... they didn’t have to do anything at all. They would have a much better chance of marrying well and/or getting a choice of men who wanted to marry them with the sort of typical education that was valued for women.
4. Paid attention to their comings and goings, and be SEEN to do so. That right there would probably have prevented Wickham from approaching in the first place. You think it’s an accident that Wickham attaches himself to the family with a father who visibly doesn’t care what his daughters get up to and a mother not smart enough to figure out he’s a scoundrel? (and no brothers who might step up either?) I don’t.
5. Taken the family to places like London and Bath where they would meet more eligible men than they would in a small country village.
But any of these would require effort on his part. They would require him to involve himself in the lives of his children. They might even require him to sacrifice a small part of his own comfort to see that his children have a better chance at a good life. And these are all things that society would have been expecting and encouraging him to do. He does none of them.
