It was OK that children were put to work, maimed and died in droves during the industrial revolution. We wouldn't be where we are today without their sacrifice!
And from that we go to "was _this_ particular thing really necessary?", which doesn't really change the main argument. Sure, they could've done without maimed children. Add 8 hour workday, weekends, maternity leave, minimum wages, social security, pensions, health care and pretty much all the things we take so much for granted I can't even think of them. Like I said, it's about wealth - some things you can afford as a country when you're US and some you don't when you're Moldova or Albania, not to mention Congo.