Now, with an eye toward the social dynamics of village life, I've always found the notion quite alienating to try to immigrate in a country where petty grievances held against me by my fellow villagers might block my path towards naturalization.
The picture is probably slightly different in more urbanized places, but, in those, it probably boils down more to a question of money.
I'm not sure what to make of your "a quarter are immigrant" statistic. Do you mean they live there, without being citizens? Is that number high precisely because the path to naturalization is so difficult? The number of non-citizen permanent residents, for example, is also extremely high in certain rich Arab countries (like the UAE), but they are effectively an underclass of indentured servants. So "immigration-friendly" is not what that kind of a statistic is saying at all.