Why are Zen and Tibetan Buddhism(s) more popular in the west than Theravada Buddhism?
Well, in traditional Theravada Buddhism it’s highly encouraged for one to become a monk, and in fact, Theravada Buddhism says only a monk can attain enlightenment. Mahayana is a little more open and relaxed, especially in regards to laypeople. Of course, there’s the Vipassana Movement, but that’s not really traditional Theravada.