Why were Kraftwerk such a colossal success?

Everything about Kraftwerk was odd. They had no front man, they seemed to play no instruments and their strange, electronic music owed nothing to blues, soul or any of the other forms of music that underpinned 20th-century pop. Instead, a Kraftwerk gig consisted of four rather gauche-looking fellows from Düsseldorf standing in a row, each poking at a synthesiser, as a strange, apparently unconnected series of images appeared on screens behind them.