there's two kinds of multiculturalism in music
there's the from-above, "take a pinch of this, take a pinch of that, mix 'em together, make a movin' flavour" approach (that's a Paul Weller lyric, possibly mangled in memory), where it's an artist's decision that they want to be cosmopolitan and syncretic. so anything from Ryuichi Sakomoto's Neo Geo approach to Paul Simon going to Bahia and working with drum squadrons, to i dunno, a much more recent example of this (Gang Gang Dance? Future Brown? the Artetetra label in Italy)... these can be well done and enjoyable to listen to, but they are never culturally generative, they never get past being the musical equivalent of fusion cuisine
and there's the more slowly hatching, semi-accidental hybrids that come about through the long-term proximity of populations - usually in a city - who are attracted to aspects of each other, learn from each other, and actually have forms of solidarity that go beyond the merely musical... they coexist in the same lifeworld
... these kind of gradual processes actually generate new forms, new tribes... lasting and fertile changes
the first (from above, eclectic) is a temporary agglomeration of carefully chosen influences, in any given record... or confined to a single artist's body of work
the second (street-level, shoved up against each other) is organic, as much a social event as it is a musical one ...
i think one of the problems is that the internet overwhelmingly fosters the former kind of fusion... it isolates and desocializes music-making to some extent, and gives people a whole world of things to pilfer and pastiche... and even worse, now it's offering the pasts of all these different cultures