BUT EVERYONE IS NICE, WE'VE ALWAYS BEEN COOL
I know. Honestly, I do. Except for minor incident that I recall, PyCon US has largely been free of issues such as this. Every meetup, conference, etc I have been to has been filled with nice, kind people and largely jerk-free. This is a testament to the community as a whole.
So, you ask: if we're all chill cool people, and nothing bad has happened, why have one?
Because it won't always be that way.
If we continue to expand and grow (and we will), and if we continue to grow even more diverse - in sex, race, creed and geography - the chances of "an incident" will grow. In fact, I know incidents have happened and been dealt with.
So no, the unspoken rule of "don't be a jerk" doesn't scale very well. And that's what we're talking about - a scalability problem. The social norms and rules of a group of five people, or one hundred people may float. What about 200? 500? 800? How about 2300 people (the attendance of PyCon 2012)? No. "Don't be a Jerk" may be our unspoken, unwritten community motto; but its not enough for those on the outside looking in.
Those outside of these circles want clear lines on behavioral expectations. They want to know that not only are there unwritten rules about not being a jerk - they want to know what will happen if a Jerk Occurs. This sets their expectations, and it gives them comfort. It makes them feel more welcome, more safe. Especially when they're part of a group who has been put under constant objectification and harassment for decades in our industry.
I completely understand the spot you are in and can see how you are rationalizing it. The policy approach just doesn't fit for me (nor does it need to). I only commented because I do care about the Python community and hope to attend this event.
When I read the article I can't help substituting "label on cup" and reading incident as a coffee burn.]
Seeing "we now have an anti-harassment policy!" followed up by "and women are specifically encouraged to attend and apply." makes me cringe.
It doesn't feel like the way to encourage my wife (engineer) or any of the numerous women I have developed software with that the conference is an awesome event.
The numbers disagree with you assertion(s) - we have increased sponsorship due to the actions taken, we have increased the number of female presenters/speakers, and we have an astounding number of thank you's from women within the community with regards to the actions taken and statements made.
I am not "in a spot" or "rationalizing it" - I have concrete proof that changes like this in combination with a massive amount of outreach has had an extremely positive effect for the community and conference.