I find this a common sentiment here. As someone who left his country to study abroad, I find it very odd.

An individual looks at his or her options, decides that pursuing education in a foreign country will result in a better future for them and their family.

And somehow restricting their opportunity and their freedom to do so is a good thing? Certainly not for the individual in question.

Personally, I think the way to prevent brain drain is not to impose restrictions on individual liberty but to compete better on the education/career market.