If you have a rich dad who can pay the $2,000/mo, but judge says, "kid doesn't
need that much..." and gives a mom less then it can cause a lot of problems. It isn't about just paying for the kid's grocery and clothing bills, but the other time costs that are involved with being the parent with custody of the child - missed work for kid being sick, taking kid to and from daycare everyday. Finding a babysitter so you can go out one night, work late, etc.
I have no problem with requiring parents to provide thousands/month for their child if the parent can afford it.