“It is, whether we like it or not, a part of ‘our’ language.”
This is my attitude. The grammarians can rail against it all they want, but the word has a long provenance and is commonly used, so it is just as much a valid English word as any other. I wouldn’t use it in a formal setting, but it’s quite silly to try to stamp out a word that is so commonplace.
A colloquial dialect, either by habit or by consideration of audience.
Consider that 'fag' or 'faggot' used to mean a cigarette. Until people started using the FRENCH WORD cigarette.
What matters most about a 'word' is, as you say, it's commonality, not it's nationality or heritage.