Anyone hazard a guess why French tunes becoming more popular?

My guess would be because of the interesting melodic content?

Many French tunes are playable on instruments associated with English / British folk music but have a different harmonic structure, so are accessible yet different.

And if you then add in the very different sounds (to the customary instruments of the English / British tradition) of the gurdy and the French pipes, giving different tonal textures as well ... Hog Heaven!