Developing nations should have restrictions on rural-urban migration. I think it should up to these nations to decide if they want to allow such immigration. Then depending on the solution that they come up with then they should find ways to either prevent or control the migration of such people.
When any country or nation is in middle of development it is important for them to remember that some wildlife needs to stay and be catered too. Development is great for humans, but damaging too much land and too much wildlife will end up hurting us in the long run.
It is tempting to see crowded cities in the developing world and simply dictate that no one else shall move to the cities. However, it is important to know that these people are migrating to the cities because of the economic opportunities present there. For most, if not all, of the migrants, more money can be earned in an industry in the city than rural life could ever allow.
I do not believe developing nations should have restrictions on rural-urban migration. I think trying to implement such a policy in a developing country would be impossible to enforce. If you can't enforce a plan of action, then there is no reason in trying to implement it. People should be allowed to migrate freely for the most part.
I do not believe developing nations should have restrictions on rural-urban migration. In the past, people have migrated for varying reasons, which has led to natural hubs that tend to be the best locations by default. Imposing restrictions and laws on people is not needed to mandate what happens naturally and often for the best.