If you look at it from the perspective that these are two territorial single people undergoing a transaction, then this is basically surrogacy, and compensation for transactional surrogacy makes sense.

If you look at it from the perspective that these people are supposed to be a married family, then it does not.

Married people and families are necessarily conjoined. Same finances, same fate. No mine and yours, just ours, and thus all money and effort contributed is shared for the betterment of the family, no single individual interests. At least, that's the ideal. It usually doesn't work out that way in the modern world.

It may be fair for a surrogate to expect compensation for bearing a child, but for a mother, and wife, part of a family, it is a betrayal of the very concept of the family. Necessarily that kind of individual self interest shows that the woman does not see herself as part of a larger whole, a family.

This dude shouldn't be asking himself whether or not his "wife" deserves money for bearing a child. He should be asking himself if she is really his "wife."

I put wife in quotes because the guy says they are "spiritually married," which is obviously bullshit, because in spirit they couldn't be more single.