A good post from Togo, I think. It is a question of reasons and scale.
If I were to turn up in France, for example, without producing my passport, does anyone really think that I would be accepted as fleeing a non-functioning country where I fear for my life from a breakdown of law and order and an inadequate health service?
Of course not! Yet we are accepting people who are saying much the same.
As has been said by others; it is a question of scale. I have watched our culture being eroded, not enriched. Yes, great to have wider foods, opinions, experiences etc.; I'm not arguing for parochialism or isolationism, but try asking the average 12 yr-old to sing a British folk song and my bet is that they can't even give you 'Molly Malone'. Rather like indigenous cultures, such as the Maoris, the host country is being gradually marginalised.