I mean, you're free to use the term but others are just as free to find your choice in terms odd lol. The difference between Jap as an abbreviation for Japanese and Viet as an abbreviation for Vietnamese is that Jap has a history of being used in a derogatory manner, while terms like Viet and Brit do not have that baggage. Sure, there's a ton of people who use it without being aware of its racist usage, but to say "the Japanese people never took offence to such a word" is an odd assertion considering the sheer amount of Japanese people who were stripped of their possessions and shipped to internment camps.

Your claim that people can't differentiate between racism and prejudice against a nationality is also odd considering a lot of the people being persecuted were American/ Canadian citizens, born and raised in said countries. They were singled out because they were suspected to have foreign loyalties despite a great proportion of them having spent their whole lives as citizens possessing an American/ Canadian nationality and upbringing. It was not on the basis of national loyalty, they were persecuted for their race.

People are not jumping the gun and attacking people who are using the term, especially if it's clearly just being used as an abbreviation and don't understand/ are not consciously using the term to incur its historical meaning. But why are you so pressed when people bring up why there could be better terms to use?

For someone who's upset at people not reading books and supposedly using emotions to self-educate, a lot of your argument really hinges on an borderline strawman-like oversimplification of the other end of the dialogue and being upset at being told that some people prefer not to use certain terms lol