It is, but unfortunately, the importance of retaining these highly educated people is too subtle a concept to express in the immigration yelling that happens at the national level. Most of my colleagues are not American, but they have to jump through hoops to remain in the US - despite being educated at public universities. We've already invested in them, the rational thing to do is to try to retain that investment.
I'm unaware of the legal hurdles immigrants have to face, never having to deal with it personally. It's upsetting to hear this, especially when we're talking about the kind of people our government keeps telling us we need. Such is the way of politics, I suppose.
I think the point about drawing internationals to America is understated. I never really thought about this, but its very true. I've personally met more high achieving, very intelligent foreigners who came for grad school and were planning on returning home, but for one reason or another ended up staying here. This is invaluable for the US, in my opinion.