Because if you dtd, then there is always a risk of pregnancy. condoms are only 98% effective, the pill and the coil 97%. This means basically that if you do the deed, then the only way of ensuring that you don't have a baby is terminating it.
And breathe.
IMO, NOT having kids is a lifestyle choice, not the other way around. If a man doesn't want kids, then he needs to always always wear a condom, even if she ison the pill and has a coil in, or have the snip. and probably still wear a condom. Or only have sex with someone who is post menopausal.