Historically, it's because of imperialism. Buddhism, for a long time, had turned into a faith religion, suffered many close encounters with dying out completely in several regions, resulting in the 3 major traditions of Buddhism we see today, the earliest version of Buddhism died out long ago.
When Western imperial forces began to systematically take over regions of Asia for trade, the Buddhist monks in areas such as Burma/Myanmar felt that this was the second time their tradition would die out, and sought to preserve the parts that they felt were essential. In their case, it was the path of vipassana meditation, and though Buddhism didn't die out there, from then on it was strongly influenced by this more refined, less faith-driven teaching.
So when Westerners started to go over to these regions of Asia, this is what they were taught, not the religious faith of the local lay practitioners, which existed mainly to support the monks in their vipassana.
When Western imperial forces began to systematically take over regions of Asia for trade, the Buddhist monks in areas such as Burma/Myanmar felt that this was the second time their tradition would die out, and sought to preserve the parts that they felt were essential. In their case, it was the path of vipassana meditation, and though Buddhism didn't die out there, from then on it was strongly influenced by this more refined, less faith-driven teaching.
So when Westerners started to go over to these regions of Asia, this is what they were taught, not the religious faith of the local lay practitioners, which existed mainly to support the monks in their vipassana.
Vipassana meditation is mindfulness practice.