Who's going to raise them? A single mother, if they're lucky. Think she's going to have an easy time re-marrying with an ex-con husband? How about getting a good job in the era of background checks? Think she was highly educated to begin with?
Taxpayers at large are going to foot most of bill for this domestic disaster. Further, these children are now more likely to end up in jail themselves. Now society gets to pay another $30,000 a year per child to house, feed and care for another inmate.
This isn't strictly touchy-feely stuff here, there's a hard cost to society when you jail people without any thoughts towards true justice. It's stupid, ineffective and perverse.