Even if we rule out the possibility of human race going extinct (which is quite improbable anyway?), isn't missing on a family life (wife and kids) quite a huge compromise in pursuit of some vague definition of 'productivity'?

It's only a compromise if you prefer kids to other activities. I have plenty of friends who have spouse and kids, or spouse and no kids, or are single (or other combinations for that matter). There doesn't seem to be a gross correlation between family state and happiness among them, although the research says that the childless are happier than those with 'em.

I'm changing the world by doing stuff other people aren't. Most people are spawning, so it seems unlikely that I will change the world by doing so.

Note: FWIW I do have spouse and offspring, and enjoy my family life, but I am not pretentious enough to think that those things are part of my "contribution to humanity" any more than driving my car is.

And what's with the sexist "wife and kids" bit anyway?

If you don't want to marry or have kids, you're not really compromising anything.

imho, it's about being honest with yourself about what you want.

Indeed. I don't even remotely fancy raising a child (or multiple). However, I understand that others find it desirable. To each his/her own.