This is a hot issue to discuss, and I've been involved in it on two other forums in one form or another ("Dave's ESL cafe" and "Young Dudes' Guide to Japan"). This forum is certainly more balanced than the latter, where I had people thinking I should work for Debito (amongst other ones)!

Strangely enough, comparisons with illegal aliens are strange ones as the people we're talking about getting undue attention are not illegally living here and are often married to citizens here. Every society often likes to focus on powerless scapegoats when they can't fight a problem or don't wish to. Why should Japan focus on a small minority of the population when it doesn't seem to be in the government interest to do so? Does tourism and foreign business investment in Japan ring a bell? Of course the latter may not be discouraged as long as they are servicing the domestic market, but they may be more than annoyed when their company seems to be competing under different rules than the Japanese ones. How do you think these cases of overt discrimination are going to make tourists want to visit here?

As to the employment issues, no it is a big difference depending on the country that you're looking at. The US has a large number of tenured foreign lecturers. Japan has very few, and even though the number of Japanese who are tenured is decreasing as well, they still have a much better chance of getting regular permanent employment here than a foreigner does.