Regardless of the politics and policies of each country, it's important to acknowledge the importance of remittances -- which can be quantified -- and information flows, which cannot.
According the the Economist Intelligence Unit:
Remittances from Hondurans living abroad more than trebled between 2002 and 2007, reaching US$2.5bn, equivalent to more than 20% of GDP, making remittances Honduras's largest single source of foreign exchange.How much is $2.5 billion? It's most of the difference between Honduras's 2008 exports ($5.6 billion) and imports ($8.6 billion) in 2008. In other words, Honduras sends coffee, bananas and people abroad, in exchange for cars, oil, cellular phones, and other things they want at home. Without migration, they would be much worse off, and that's not even considering the value of knowledge and wisdom that passes from extranjeros back to their friends and family.
Bottom Line: Migration is very important to the development and quality of life in less-developed countries.