Neo-Pagan practices were kept private because in most places they were illegal and seen as an affront to the Christian Church. Publicizing one's connection to these practices could get one killed, or at the very least persecuted in some fashion.
Sadly this type of persecution still occurs today. In many parts of the world, admission of being a Witch or even the mere accusation of being a witch can still get a person killed, raped, maimed and jailed. There have been several occurrences of entire towns stoning or assaulting women in India who were accused of being witches. There are cases of murder in the Middle East. And even here in the US, those who publicly proclaim their pagan beliefs can be persecuted by ignorant bigots through custody battles, harassment at work, or even losing their job. One need only do a google search for news items that tell the story. So many still keep their practices in the broom closet only sharing their secret with those they trust.
For those of us who live out in the open, there maybe several reasons we do it. Some of us feel pride about our beliefs and chosen path. We are ready to answer questions, and use events of conflict as opportunities to educate and bring about tolerance and clarity of what we really are. Others may do it out of a sense of rebellion, or a need to be seen as different and part of some exclusive club. And others may do it because it's the latest fade or they want to be like a character they've seen on TV or in the movies in an effort to be more than what they think they are.
I don't think these reasons are any different than any other path, or any other expression of the self from the past. The same reasons for living out in the open can be said for the 'Hippy' era, or for the Gay and Lesbian community. The topics are different, but the expressions and reasons maybe the same. We all face potential persecution by ignorant bigots, yet we are all still proud of who and what we are.
Those that choose to live a path they don't understand (the fakes and playgans) will either be found out and identified as being wannabes, or they will lose interest and drop the act for the next new fad.
For my part I can say that I have faced ignorant bigotry in a work situation. But I gained more positive experience from that situation as most of my coworkers came to my defense and the offender was fired from the company which has a no tolerance policy relating to harassment of religion, race, gender and sexual orientation. But this and lesser conflicts have not caused me to feel I need to go back to the broom closet. Rather they have given me encouragement that those of us living publicly are making a difference and paving an open road for those who still feel uncomfortable.
Just my 2 cents and humble opinion.