Of course not. In fact I would say that people should not have children until they reach the point where they desperately want one! Having children may be the right choice for some people but that doesn't mean it is the right choice for everyone. From a biological point of view, what's important is that the species reproduce, not that every individual reproduce. My brother never had children, but my own children carry some of his genes anyway.

It is definitely not a necessity. Some people would like children, some people don't. And either is completely fine!

Not really. The world is already overpopulated as it is, and to be honest, children are such a hassle, I mean for the first 3 to 4 years all they will do is cry and run around and then you'll have to deal with school and whatnot, not to mention, having a child is really expensive, just imagine the things you will have to pay for. Well, then again, I'm just a humble chicken, what do I know?