Historically Japanese used to call foreigners 外人 (gaijin) which means foreign person.( or if you wanted to be more specific it technically means "outside person" 外 means "outside" and 人 means "person" though 外人 mostly gets translated as "foreigner" by google translate)
And then over time 外人 was considered to be "rude" and "politically incorrect" because 外人 refers to anyone that was not of Japanese ethnicity even if they had Japanese citizenship, so they started saying 外国人 (Gaikoku jin) which means "foreign country person" (or outside country person though again google translate translates it as "foreigner") which is the term used by the Japanese government and media. There's still people who say 外人 but the mainstream term is now 外国人.
And now there are those that even take it one step further to start saying 海外の人 which means overseas person.
So who exactly was responsible for the political correctness being pushed over there?
This is similar to the bastardization of language in the West. its like how "illegal alien" started becoming "illegal immigrant" and then it became "undocumented immigrant" or even why the West doesn't even describe foreigners in their countries as foreigners anymore, or how "transvestite" became "transgender". Political correctness became so bad that even conservatives stopped using "illegal alien" and started using "illegal immigrant" similar to how even in Japan conservatives started saying 外国人 instead of 外人 even though they are clearly still using the term anytime they see anyone that doesn't look of Japanese ethnicity.
Idiomatically and within the usual context/level of politeness, it means "outsider".
To my understanding, it actually is derogatory in it's original context, so I wouldn't push this implication of being changed as entirely bad. Unlike racial slurs and epithets, it has a more universal touch of "someone not from our society". If you're saying it to someone, it's like saying "what's this fucker doing here, should go home to their own country". It would be similar to an American telling any legal tax-paying, freedom-loving conservative immigrant who came here through all the proper means, that they're an "outsider", simply because they don't look white or clearly are from Europe. There is some racial attitude about it, but it can apply to anyone determined to not be from Japanese society itself.
If anyone's pushing it, it probably the media. That's usually where the core of foreign influence starts where there's external control. Could also be the Japanese themselves, if they're believing in globalism and also believing in general politeness. Japan's economy is shit too, because they won't take themselves off the global banking cartel chain, so could also be wanting to do business with "outsiders".
EDIT: You nigger down-voters are wrong about this. Actually immerse yourself in the culture before passing judgement on what you swine think is really going on.