The owl brings up a good point. I don't mind summoning a dark lord and goat blood has a pleasant tangy smell to it, but I'm not into asphyxiation. I get enough of that at work and play. There's a time and a place, y'know?
Logic would agree with you, but for most women, finding a doctor who will do it for you if you are under 35 is almost impossible. Most will argue that "you might change your mind" or just flat our refuse. I've heard way too many stories from friends who basically had to switch multiple doctors, travel out of state, and wait years to get it done.
I suppose if we're being fair, a vasectomy is a much less invasive procedure than tubal ligation. There are a number of risks associated with tubal ligation that you just don't have with a vasectomy---so there are perfectly valid reasons why a doctor might balk at the procedure and not at a vasectomy. That said if the woman is 100% healthy and willing to accept the risks, go for it.