As to John's question, perhaps the bowing colored his first impression of the dojo and it's what stuck in his craw. After that, the class was just a swirl of things he didn't understand. There are people out there who didn't join because they didn't like the carpet. I'm not sure why they even came though the door; there must have been some attraction. Unfortunately sometimes the attraction is overwhelmed by some little thing. Perhaps it's just that they aren't ready to commit and are looking for an excuse.
I've asked people why they joined and have gotten everything from "the dresses looked cool" to "you used a pizza analogy".
About the bowing, I notice that most Japanese dojos have the founder's picture outside the kamiza/kamidan, usually somewhere above it, off to the side. I wonder if this practice would do anything for the idolatry issue.