Alternatively, some people come to see the err of their parents' ways and realize that in spite of their good intentions, they lacked the emotional maturity to build (a) a healthy marriage and (b) a nurturing environment for their children. I love my parents but realized in my late 30s that many adults are just large children with gray hair. What's important is understanding how you may have been impacted, breaking the cycle, and trying to do better.
In the same way that one can learn a ton from being part of a failed project at work, the same applies to those raised in a less-than-functional home. I'd also say that healthy debate (read: experience arguing with family) can foster skills in conflict resolution. Make lemonade from those lemons, folks!