I think you're generalizing too much. It may be true that some kids do better in the traditional 2 parent family setup, but there are many others that do just as well in a single parent home. My parents weren't married for long. In fact, though like most married couples they started out all lovey-dovey, things got to the point where they just couldn't stand each other. Then the arguments and the fighting started---which happens a lot in many marriages, and that shit definitely has an effect on the kids. After they separated they became better people and even good friends. We went to live with our mother, but even though our dad no longer lived in the same house he was still around a lot. And we turned out ok.
I'm a single guy who's been thinking about adopting a kid, and I think I could do a good job as a dad. All depends on the relationship you as the parent have with your kid. You have to teach them values, manners, and respect, and you have to give them room to grow and to express what you teach them in their own way, as a part of their individuality. Most important, you have to make them know that you love them. They may act like they're too big to care about that but that validation is extremely important to them. Thats how my parents did it. Kids are not wild animals. If you put your foot down and reason with them about things in a respectful way, most of the time they will listen to you. You just have to be consistent.
A lot of what is happening with kids out there now isn't just because they're from single parent homes. Its because the parent aren't as active in their kids' lives as they should be and because they're relying on TV and school teachers to do the parent's job. Even more depends on the type of friends that parents allow their kids to associate with. If you hang out with trash then you will eventually become trashy yourself. If I ever acted out and was rude to a teacher, my dad would have kicked my ass...well, maybe not literally, but he would take me aside and have a stern talk with me to let me know that that behavior was inappropriate and unacceptable. Then he would make me apologize to the teacher.
Kids want that kind of discipline. Most of them just don't know it. They can learn that direction just as well from one parent as they can from two.