To have or not to have

When I'm planning when to have a baby, one question pops up in my mind: why do people want to have children? (regardless of those who want to have heir to continue their family line, or those who want to have someone to manage their funeral) 

There are already so many humans in this world, so many problems among humans, and so many problems CAUSED by humans, that we haven't solved. Moreover, it adds more worries and burdens to our life (more pain for my wife). So, why do people still want to have children? Any reasons for me to have a child? Wouldn't it be better if we just adopt orphans?

We haven't decided still, and right now I don't want to think about what our parents might think. But if one day I have my own child, I think the only reason would be: there will be another awesome fella in this world to help make the world a better place. :)