I think that there should be one more factor to consider. Many city Catholics attend a large church building where often no one knows or speaks to the other person. There is no sense of community or fellowship in many of these churches. While it may be true in some Protestant churches as well, most Protestant churches usually offer a little more friendliness and warmth.
Jehovah's Witnesses usually overwhelm a visitor with an appearance of Christian love and concern. If a person is not familiar with this kind of reception, they come away very impressed and interested. This was my first impression. And when coupled with people who were really interested in religion as a "way of life" rather than just a ritual, I was convinced that this was "the truth."
It was only years of observing questionable conduct and the superficiality of this "love" that I began to have doubts. But in the begining it was a powerful draw.