Discrimination?

Recently I've taken part in a Usenet discussion where some of the participants were of the opinion that Israel's policy of allowing unlimited immigration of Jews is somehow more discriminatory than Germany's policy of allowing easier immigration for ethnic Germans, or Finland's policy of allowing people to immigrate because they are ethnic Finns, etc. Of course they are wrong, but that's not the point here. Here is the question:

A lot of Western countries have some kind of relaxed immigration rules for people that they consider ethnically "theirs". This comes in many forms: Finland admitting Russians whose passport and/or birth certificate says they are ethnic Finns, Ireland admitting anyone who had an Irish grandparent, and giving citizenship to anyone born in Northern Ireland,
Israel allowing unlimited immigration of all the Jews and their families, France and Spain having different immigration rules for people from French-speaking and Spanish-speaking countries, etc. It is considered absolutely normal and very few people ever question it.

Why, then, would everybody be so pissed off and screaming about racism if a country had a special immigration program for whites (or black, or asians, for that matter)? Not that any civilized country has tried it recently, but I am pretty sure there would be an outrage if anybody did. Hey, my own first emotional reaction would be "argh, fucking racists". What is it in giving preference to whites that pisses us off more than, say, giving preference to the Irish?

Another interesting detail here is that it is considered completely kosher to make immigration easier for people who are citizens of predominantly white countries, as long as they are not actually selected by race.