I'm really torn on this one. I can see the education benefits of a coming out day. So many can be reached who didn't realize this option was open to them, and so many can finally get a sense of "the way I feel isn't wrong".
It would really depend on how it's orchestrated though. As was mentioned before, a spectacle atmosphere wouldn't serve to promote education and acceptance so much as a "let's look at the freaks" attitude. I live in NYC where they host the gay pride parade each year and where so many people go to "look at the freaks". It sometimes upsets me as a bisexual that people are running around almost naked, making out all over eachother, dressed in ridiculous costumes, and more are not walking down the block with their partner dressed as every day people holding the hands of their children. Yes, people should all be accepted for who and how they love. But what tolerance are you promoting by making yourself a "freak" in the eyes of the "normals"?
For myself, I also worry about the lack of a clear concrete and universally accepted definition of polyamory. I don't want to be in more than a triad nor could I emotionally handle more than a quad. But there are people out there, even on this forum, involved with three or four or more other loves, ranging from deep emotional commitment to the swingers who call themselves polyamorists and everything in between. While I don't object to their life choices, do I want them standing up and representing me? Maybe not. I think that would actually make it harder for me to come out to more people, if the public view based on this coming out was so different than my own personal approach.
I've come out over time to a good number of people, all on my own, and in my own time. I've gotten varied reactions and dealt with them as they came. There are people I will probably never come out to and I don't feel as if I'm living in a closet by not doing so. It's just a personal decision on my end who I'm comfortable with knowing and who I'm not. Yes, if it was more socially acceptable I might come out to more people. But how does one go about making it more acceptable but by living your life and leading by example?