This discussion is about national identity - i.e. self identification. So it has to do with self perception, and the way Americans relate to the immigrant experience is very, very different than the way the French do. To take one example, the political calendar of NYC, and every other old line city, is littered with celebrations of its constituent groups - St. Patrick's Day, Columbus Day, Puerto Rican Day, gay pride day, MLK day, etc - waving their flags as they march down Fifth Ave, with every local politician jockeying for a place at the front of the parade. Affirmative action and de facto ethnic quotas have a long history here predating the Civil Rights movement and were used as a way of integrating the various groups.
I fully agree with what you say on national identity. The one thing I don't like is when Europe in general, and France in particular, is described as a place not welcoming to immigrants, which is the logical next step (which YOU did not make) of the point you state about integration. In the long run, we're all dead. John Maynard Keynes
Well I might make it, though it would be even France, not particularly France, - I think it's pretty clear that there is considerable anti-immigrant feeling in France and that there is a racial component to it - but that's obviously true in the US as well. In fact just now it's been stronger in the US, but that goes in waves in both countries so the reverse has been true as well.
I also think that Germany is substantially more unwelcoming than either France or the US - think of the Christian Democrats campaign against changing the law to grant children of long term permanent residents citizenship.
Where I have problems with France has to do with my liking of the hyphenated model, and my instinctive distaste as an American liberal for what is effectively a model very similar to the one promoted by the pro-immigration faction of the US right, albeit embedded in a very different historical context. I think that some parts of the US liberal model - namely affirmative action or actually allowing the governent and researchers to collect data based on categories of ethnicity and race - would be helpful in France, and feel that there is a bit of a kneejerk little c conservative tendency to reject such changes out of hand. Other parts, like ethnic and race based political mobilization, which has been one of the most powerful integrative forces in the US, probably aren't transplantable to France's political system and culture.