Peace ravage
If they are bad parents then they are bad parents. The number of children was determined by Allah (SWT) not by them. Besides you are using examples of people who have breached the 4 wife limit.
I know a family from Nigeria, the father of whom is the second richest man in the country at that time. He had four wives and 30 children. By Allah (SWT) I could not see such beautiful characters in any people than I did in his children.