The thing about Paki is that, in origin, it is exactly the same as, for example, Aussie.
The reason it is an term of abuse in the UK is that it was used as a term of abuse - and not just for people from Pakistan, of course, but anyone of South Asian origin. It just happened to be the word "paki" that got adopted for this. It could have been something else.
It's certainly believable that in another country that had never used it except "properly" as a short descriptor for people actually from Pakistan, and generally connected to sport, it would not have any such connotations.
In today's world, of course, borders are blurred and people are far more aware of what happens elsewhere, but why are people in Pakistan offended by it? This is a genuine question; I am not disputing that they are, but I am interested to see how it came about. Is it because they are aware of the UK usage, or is there another abusive usage where people actually apply it negatively to Pakistanis as a national group that they are aware of (and I am not)?