Because it appeals to the Italian express coffee (Caffè espresso italiano)  

From its beginnings, espresso has always been a symbol of passion.
Originally a product of Italy, it has grown rapidly in popularity worldwide due to its emotive qualities. The perfect sybthesis of aroma, flavor and body make it a multi-sensual experience comparable to none.
Surprisilingly low in caffeine, espresso stimulates trought the awakening of the senses. It evokes a refreeshing feeling of reneval and vitality and offers a rich, velvety smooth presentation that equals it taste.
Crafted well, espresso lingers just long enough to be enjoyed after the cup is empty.