Why can't the goal just be to get the best speakers available? They know what their local community is most interested in and I assume would be inviting speakers based on that, not any type of racist or sexist agenda.
I spend some of my free time doing international recruitment for my alma matter. One question I get asked occasionally is about affirmative action, which is effectively what we're talking about here. To be honest, I don't find the post-mortem being linked to particularly productive or helpful: if anything, it shows a lack of empathy:
> "It doesn't matter who speaks at a conference, as long as they're capable, interesting and relevant. That's what matters: content, not style"
This is a frequently made argument against affirmative action. It's based upon the assumption that the only purpose of college (or, in this case, a conference) is to learn. However, that's not true. Conferences provide social opportunities, and a chance to interact with your peer group. Some people argue conferences are primarily networking opportunities first, learning second.
Because of this, you ideally want to attract as wide a group as possible. Organizers can attract this wide base by providing a diverse group of speakers.
There have been in the past several posts here on HN about women being treated very badly at conferences. We know that sexism (and racism) can and does happen. Ensuring that your conference audience is diverse can help mitigate this. To have a diverse audience you need to consider what barriers might exist: perhaps an all-male caucasian panel is one such barrier.
> "Turns out, a lot of the famous Rubyists are white guys and all of the ones who said they'd like to come were, indeed, white guys."
This may well be true. But perhaps the pool of speakers was rather self selecting. Colleges like the one I went to spend a considerable amount of time and money actively engaging with minority groups, because those minorities might not otherwise consider applying. The same is true for conferences.
If you're organising a conference, or any public event, you need to be aware of these. In the UK you're required by law to have a disability access policy for your public event: why not spend the time to put together a diversity policy as well?
This whole situation is very sad. I don't think the conference should have been cancelled. People could have approached the organisers with their concerns in private first - it doesn't look as if this happened. Stuff snowballs on Twitter. Nobody comes out smelling of roses here.
However, it does also seem that the conference organisers didn't give particular thought to diversity at their event. The bottom line is these are very sensitive issues. There is no right answer. This sounds like a cop out, but it's true: if affirmative action has taught us anything it's that somebody will be unhappy with whatever approach you take. That somebody may not always be morally or ethically right, but they will be vocal.
"Using data from audition records, the researchers found that blind auditions increased the probability that a woman would advance from preliminary rounds by 50 percent. The likelihood of a woman's ultimate selection is increased several fold, although the competition is extremely difficult and the chance of success still low." http://www.princeton.edu/main/news/archive/A94/90/73G00/
The question to ask is whether the conference organizers made any efforts to do something like this, or whether they assumed that because they are nice people all their decisions must be completely unaffected by any consideration other than the most objective judgment of presentation quality. Many naive people believe their motives are pure but inevitably they're not for any human who actually exists in the real world. We all have to do some work to compensate for that.