Well there are good reasons for immigration beyond ideological. The biggest one is probably population. Most EU countries have either a stagnant or negative birth rate. These countries offset this by taking in immigrants. In the past these have come mostly from Eastern Europe, but as many former Eastern Bloc countries begin to see their own negative birth rates, sources outside of the EU will need to be found. Increasing the birth rate again is far from a simple affair, and population stagnation/decline is what has made Japan so weak in recent years, while Germany has continued to grow. From a purely pragmatic viewpoint, immigration, at least when properly controlled, enables a country to add more consumers to its economy and more people to the workforce. While this is not strictly necessary for countries with high birth rates, it is important for those with lower birth rates. Without immigration, countries like the US and Germany would stagnate, decline, and slowly start to crumble. Even Japan, as xenophobic as they are, has begun to realize this and is now taking in small numbers of immigrants. Russia has the same inherent population issue as Germany and Japan, but their issue is that many immigrants don’t want to move there. The country has a middling happiness record, its a de facto dictatorship, and its potential for economic growth is quite limited IMO. China is also beginning to have population issues, hence why they’ve been so keen to get into Africa (gives them a new, reliable consumer market and potential source of immigrants, not to mention the resources).
In short, the West takes in immigrants because they need them the most. Saudi Arabia doesn’t take in immigrants because they don’t need to. Its not an issue of races and homelands, its just pure consumer economics.