Actually, it's not acceptable from a national security standpoint to massively let a country's citizen flock on US services, at least as long as the NSA/CIA exists. The internet does need much more competition on all continents, including for webmail services. For example I don't see why my government (in Europe) should accept tax reports with a US email (because everybody has @gmail.com or @hotmail.com) – Why not at this point go all the way and delegate our tax collection to the American IRS...

On the other hand it has to go towards privacy, choice and democracy. Obviously cutting your citizen from the international websites is the one wrong way to stem local competition...