Yeah, all kidding aside, it's all about keeping control of your life, making a conscious choice when you want to have children, as opposed to life "happening to you".
There are of course lots of other contraceptive options, but as we like to say, nothing like a multi layered defense... where the lady is "on the pill" and the guy is wearing a condom.
You can also both get "fixed", but in the case of men and
vasectomy at least, according to doctors I've talked to, it's not fullproof. First, it takes something like 3 months to know for "pretty sure" that you're firing blanks. And get this - years later the body can MAY at some point "fix itself", i.e. the tubes can somehow get connected again.
Of course, on the vasectomy front, I only have one thing to say... titanium balls!
Yes, I did ask the doctor if the "small titanium clamps / staples" would go off at the airport. "don't worry folks, it's just my titanium enhanced balls; nothing to fear". :)