Last time I was thinking about it, I got to a more optimistic solution... but time will verify what is true. A couple of ideas: If someone moves around, he/she's probably more capable of adaptation than many others. He/she's probably also more intelligent than an average Joe. They're also less likely to have a family and probably around the age where they might want one. So it's quite probable, that it's really a migration of talent. This talent positively influences the destination country (as do the taxes you pay there)... In the end - one might hope that by migrating, you're not only helping themselves, but voting with their actions and supporting the laws they accept...

Oh well... time to go back to reality ;)