See, that's where I see it the other way round. If we can't support our own citizens, we still don't kick them out; we do our best. (Sort of, anyway.) I think we should see spouses the same way: welcome them, consider them part of us, and then ask the questions about how can they live, just the same as we ask those questions for our own citizens.
Because the spouse is part of the family unit. Husband and wife are not completely independent persons. (Though we're moving more that way as a culture, but I strongly disagree.) So we're either welcoming or rejecting the family. It's a bit like saying to a daughter in law, "you're not really part of our family because you're black. ... But we'll let you in if you're absolutely certain never to be a burden on us." And to the son (in this example), "If you choose to marry that... person, you're on your own. Don't count on your friends and relations any more. You can make lots of money and do what you like, or you can leave her and come back to the fold."
Edit to add: if the example using ethnic prejudice seems unfair, you can read instead, "You're not really part of our family because you're French..."