Richard, the terms "cultural imperialism/colonialism" are not helpful in our discussion, someone could accuse you of suppressing "Freedom of choice/songs".

Nobody is forced to sing a song from a foreign culture among us here - everyone does it because he likes the song.

Your original question - why people prefer foreign songs - is a different pair of shoes.

Maybe the fact that it is a living tradition accepted by everyone (not only by a minority = folkies) is what attracts people to irish music.