That's the crux of reality to this revenge. He did pick women that won't fall into the same dissatisfied trap as the original mothers, especially being willing to fight back in ways that the originals didn't, but he also picked women that would be generally loyal and good wives if the ex-husbands just didn't lapse back to their bad habits. So he had an excuse he was satisfying the women's vengeance, but he personally doesn't actually want to make them miserable - otherwise leaving Zektor a slave was the best option.
As for the guy complaining that the mothers taught nothing to their children, the Hero Zech clearly ignored his mother in every flashback, what were you expecting him to learn? As for the others, They know how to take care of themselves... to the standards of this world. The mangaka made it look rather drastic, but the parts that are unraveling is that the girls don't look extremely better than all the other women when they don't take care of their hair (Celes did that for them), they're cooking is average (With one person unable to cook), etc. They aren't talentless, it's just that they never gained experience taking care of themselves because Celes the 'dorm mother' had been doing it the entire time. It's like having a housekeeper your whole life - sure, you learned the theory of what you should do, but actually doing it after firing the housekeeper means you get results of people doing things for the first time. In the WN, at least, the four ultimately have to face the facts that they were spoiled brats who got used to being treated well by a guy that is a hardcore house-father.
