Promoting Heritage Languages is a popular issue with certain educators. Something they can feel good about. I suspect part of the reason is ideological. To me, it seems part of the multicultural impulse, the idea amongst some intellectuals that the dominant culture in Western societies is somehow, all by itself, inadequate, and what is needed is more cultural diversity to water it down. Of course, any watering down of the dominant culture of the countries of origin of the immigrants is considered a bad thing. MacDonald's restaurants in China or Thailand are bad, but Chinese or Thai restaurants in the US are good.
In this world view, assimilation, and I mean voluntary assimilation, by immigrants is a bad thing, and retaining one's culture of origin is a good thing. Not just a matter of personal choice, but something the immigrant should do.
Now Rice University has produced a study that says, amongst other things, that immigrants who do not maintain their heritage language are less healthy than immigrants who do. I do not believe this for a second. Most adult immigrants retain their language, and many young immigrants, as was my case, do not. I doubt if it affects their health.
Don't get me wrong. I do believe that it is a good thing to learn another language. I believe that we benefit in many ways. I just do not think that whether the second or third language we learn is the ancestral language matters at all. It is just a matter of personal choice. That is how it was in my case. I am only now learning Czech, the language that my parents grew up with. This will be the 13th language that I am studying.