Parenting licenses

Parenting licenses—that is, requiring permission to have children—is a concept I think is not only morally acceptable, but morally good. A lot of people have a very negative reaction to that statement, but I think it's a very reasonable idea that, unfortunately, is very nearly impossible to implement practically. Also, when I say "prevent people from having children", the method is unspecified—do not assume I am speaking of sterilization or forced abortions. With that said, this post is about the abstract concept in moral terms, unmuddled by practical concerns.

We already say, as a society, that people don't have a right to raise children. If parents aren't doing a good enough job, we as a society reserve the right to revoke that privilege, to take the children away and place them in the care of the state. I think it's a very small jump from saying that people don't have the right to raise children to not having a right to have children.

The issue is, at its core, the same as with foster care: children's rights. Children have a right to a childhood free from abuse and neglect. Parenting licenses are based on the concept that if a child has no chance of having a decent childhood, they should not be conceived in the first place. This concept is already present as one reason for abortion—if the mother does not think that the child will have a proper environment in which to develop, she can terminate her pregnancy to prevent that from happening. People can voluntarily give up their children to foster care, but in certain cases society can force it upon people to protect the child's rights—and in analogy to voluntary abortions, society should be able to (in an ideal world with ideal methods) prevent people from having children.

Now, on to the objections. A lot of times that I bring this up, people's first reaction is a very strong but very vague objection—they think it's wrong, but cannot provide me with a coherent thought as to why they think it's wrong. I imagine this has to do with very base biological instincts relating to procreation.
Most objections relate to practicalities—that it would be excessive government intervention, a tool for oppression, classist, etc. None of these are arguments against the morality of it, only against any actual implementation of it. I have yet to hear a coherent argument against the fundamental morality of parenting licenses, and welcome anybody who wishes to provide me with one.
I agree wholeheartedly that parenting licenses would be a bad idea. The first issue that comes before all others is how to determine who is fit to be a parent. Such a psychological evaluation would be incredibly complex and would surely give many false positives. Beyond that, the methods used to control fertility are another huge barrier—we would need near 100% reliability with a near 100% certainty of re-enabling fertility. IUDs come closest to this, but I would be opposed to a system where the prevention rests solely on females. Finally, the potential for abuse is enormous. Not only would it probably tend to be classist (the argument that there is a certain level of funding that a child deserves is a pretty easy one to make), but it could easily descend into eugenics. So obviously the system cannot be implemented, but that has no bearing on its morality.