I think that they should because they should not let their people start moving anywhere they feel like it until the city is properly populated so as to not bring unbalance to the their society. The nation should wait until it is evenly distributed with people before they start allowing migration to the suburbs.
There need to be limits on how many people can be in a given area. There are a lot of factors that effect this. One is simply can the city's services handle it. From sewage, electricity and housing to police and fire departments. If everyone just could move in and not care if they have a place to live there would be chaos, overcrowding, disease, crime and a lot more problems. Now if the city can handle the influx there is no reason to not allow it. In the U.S. there are laws and regulations that limit the zoning and development of land. Something similar can be used in other countries, of course adapted to their unique needs.
It is all good and fine to say that the nations could control immigration, but is that even practical? If someone wants to move from the country to the city, then they will figure out a way to make it happen. Restrictions would only make the city seem more attractive.
I do not believe it is appropriate for ANY nation to put restrictions on where their citizens live/migrate. I believe the natural trend of a developing nation will follow that of developed nations, which is most people migrating from rural to urban areas as the country develops. I think restricting this migration restricts the country's ability to develop along normal patterns.
I don't think that a developing nation should be concerned with rural and urban migration, and the relationship thereof. A developing nation first needs to worry about its citizens in general and the services in which it provides, not where its people are going and where they are choosing to live.
It's not the people that's the problem! The problem we have here is pollution. Does an increased demand for electricity and transportation increase pollution? Sure, but as long as our energy production causes pollution, there will be a problem. If our energy needs were met through renewable energy, we wouldn't have this problem!
It is all good and fine to say that the nations could control migration, but is that even practical? If someone wants to move from the country to the city, then they will figure out a way to make it happen. Restrictions would only make the city seem more attractive.