I have read that the issue is less about Ameican citizens but more about green card holders who could become American citizens easily but don't do so, because, amongst other reasons, "a green card holder can leave the US at any time, give up her green card, and thenceforth never have to pay a cent in US taxes, or even file a US tax return, ever again. Again, this is an option which would be valued extremely highly by many Americans. By becoming a US citizen you essentially give up that option".
http://blogs.reuters.com/felix-salmo...s-citizenship/
Change the tax laws?