Can this be expplained by an idea of 'national taste'? I have heard people argue that Chilli became widespread in india as a means to mask bad tasting meat, this seems unsatisfactory to me as people surely ate bad meat in early modern Europe. Could the avaliability of spices in the east have meant that asians were more accustomed to strong flavours and as such better prepared to incorporate the chilli into their cooking?
Chillies are thought to have originated in South and Central America before being spread eastward along trade routes through Europe and Africa by the Portugese in the 1500's. The Asian trade outposts from back then remain centers of chile consumption to this day, and these regions take great pride in the heat of their cuisine. You are correct that chillies were used to mask the "off" taste of bad food, and that prior familiarity with pungent spices in these regions allowed seamless incorporation of these chillies to play an integral part in their popularity.
As to the geographic divide of modern-day chile consumption, you might consider the effect that capsaicin (the "heat") has on the human body's cooling mechanisms. South Asia's climate is hot and humid, and the effect of eating chillies is an increase in sweating - the body's natural cooling response. This cooling response isn't really necessary (or even desirable) at higher latitudes like those found in Europe.
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Great question! Fortunately, it was asked and answered not too long ago.
Feel free to ask further questions!