It's wrong and selfish, and I don't believe any man used that way should ever be legally compelled to give the woman a single penny for child support. It's equally abhorrent for men to purposely sabotage birth control in an effort to get a woman pregnant against her will...perhaps even more so because he's knowingly putting her health at risk through pregnancy.
That being said, fortunately a new male birth control is in the works and I hope that men take advantage of it. I think that if both partners are taking what preventative measures they can it not only lessens the chance of accidental pregnancy but also pregnancy through subterfuge.
If both parties are on bc and using condoms but she still gets pregnant, then the man should demand a paternity test to be sure it's really his accident. That might sound hateful and accusatory towards women but considering that there's no doubt who the mother is when a woman gets pregnant, it's not unreasonable for a man to want to know that the child that was conceived under such odd circumstances is actually his child before the government can garnish his wages to support it for eighteen years.
It isn't uncommon for men to discover that they aren't the real fathers of children they've been raising or paying child support for. You'd think all legal requirements to support these children would be nullified but I've read a surprising number of reports and articles about men who were forced to continue supporting offspring that wasn't theirs.
I don't think it's any more acceptable to use men for their wallets than it is to use women for sex, and nobody regardless of gender has the right to use another person as a stud or brood mare.