The migration restrictions you mention were to maintain cultural norms. Similarly, I think it a good idea to restrict Islamic migration. When people migrate, as I have done, they don't change culture.
Their children do if they are immersed in the new culture, but if the reasons for their ancestral culture are strong enough, they don't. For example Jews maintained their culture for centuries in their adopted countries. Moslems do too. When there is mass migration, as there was from England to NZ, the immigrant English did not become Maori. If mass migration from China booms, NZ will become a province of China. Considering how China is run, that's a bad thing.
The Europeans are now learning to their cost that immigrants do not just become locals with the same values and cultural norms of the locals. Islamic Jihad maintains the ideology.
It's fashionable now to criticize migration controls of last century, but as the USA is finding with large scale Mexican migration, mass migration changes the character of a country and its politics. To see what the new country will be like after mass migration, look at the place the new people came from. It won't be quite the same, but similar.
Humans are not clones and are not fungible, contrary to current mythology.
Mqurice |