Interesting discussion. The practice of putting music into genres is frequently problematic as there are no hard and fast rules and there is so much crossover between previously clearly distinct genres. Does putting something in one genre mean it can't be in another? Surely a rose by any other name....
I think "world music" is a particularly difficult one. Does anybody set out to record an album thinking "oh, this album is going to be world music"? I don't think so. I've never heard of Deep Forest, but I'm presuming they consider themselves techno/dance, because "world music" is a term we've applied to them because they aren't from the same part of the world as us, perhaps more relevantly they don't share the same musical traditions as us. Bringing me to another roblem of world music... who is this "us"? Clearly, in Senegal, for example, Senegalese artists aren't considered "world" artists.
Despite the clear problems, I'm extremely thankful for the genre as it's literally opened up an entire new world of music to me. For those looking into an introduction to world music, I'd really recommend the
BBC Radio 3 Awards for World Music albums, they do a great job of breifly introducing and showcasing the enormous range in world music and are a wonderful way of discovering new artists and styles.
Some personal "world" favourites:
Yasmin LevySouad MassiOjos de Brujo