A.K.A., let's revise the panel description right here.
When I first read it, this panel description:
Hidden Biases in SF
Why aren't there more blacks or Asians, Jews or Catholics or Muslims or Buddhists in even our most richly imagined futures?
Tobias Buckell, Gregory Feeley, Gregory Frost (m), Daniel Kimmel, Pamela Sargent
made me immediately say "Oh look, I could play Bingo!" Being cranky and wanting to get through the rest of the panel descriptions, I didn't think about it any further. But a comment of 
desdenova made me think more about why I had that reaction. While there are problems with that one sentence as it is [*] , my reaction boils down to that useful phrase from Pratchett's most recent book: this is the wrong sort of question.
[*] "Our most richly imagined futures," says who?; why is this being restricted to race and religion; what about multi-racial people; I prefer "black people" (etc.) to "blacks" (etc.); and probably more, because I have my own biases and defaults that I can't always spot on first glance.
The reason it's the wrong sort of question, it seems to me, is that the answers it invites are predictable and already hashed-out. Why aren't there more SF futures with characters drawn from more diverse existing groups? I can only think of two categories of answer to that question:
- The author just didn't think about it.
- The author thought about it, but decided not to.
And the subcategories of #2 are all things I've heard before (nb. mostly with regard to race; if they get deployed differently with regard to religion, since the panel topic specifically called out religion, let me know):
- It's so far in the future that:
- everyone will be the same color anyway (not true) [**];
- religion will have died out as incompatible with space-faring rationality (hello, insulting lots of people including Guy Consolmagno!);
- Mentioning characters' skin colors makes a work "about race," which is not what the story is about (because, e.g., The Orphan's Tales, Patrick O'Brian's Aubrey-Maturin series, and Rainbows End are all works that are "about race" just because they mention the skin color of their characters </sarcasm>);
- Mentioning characters' skin colors just reinforces racism (no, it just allows people to continue using their unexamined cultural defaults);
- Authors will get yelled at for cultural appropriation (maybe, but they also might get yelled at for getting physics and biology and language wrong, and that possibility generally motivates them to do research on, and think carefully about, physics and biology and language, doesn't it? Also, all these links and more).
- SF is diverse 'cause it has aliens! (are you seriously saying that you find it easier to write or relate to a literal alien than to me, the human right here in front of you?!?!)
[**] I realize that this conflates race and skin color. Two things about that. First, even if a book is set so far in the future that there are no recognizable influences of any present-day groups, I'd still expect people to look different from each other unless there was some really major SFnal reason to the contrary. Second, a lot of the discussion I've seen conflates the two, as in the subsequent points.
(After writing most of this, I found this FAQ from the blog Ramblings of an African Geek, which has additional common arguments.)
In other words, I think that the answers this question invites are very 101-level. And maybe that's what Boskone/the proposer of the topic/the panelists intended, which would be fine. But the prospect of sitting through a 101-level debunking does not thrill.
What's the right sort of question, one that would move this past a rehash of FAQs or bingo-playing? My first thought is:
What are useful ways of identifying and addressing hidden biases in SF? What are the resulting benefits to writers, readers, and stories?
But I'm not quite satisfied with that. What do you all think? What I am missing? What panel description do you think is likely to produce interesting, thought-provoking, non-head-desking discussion? What questions would you like to see answered?
(I am sending a link to this to the only panelist I know, and to Boskone itself; it's almost certainly too late to get the formal description changed, since the program is going to print tomorrow, but it's not as though panels haven't turned out different from their descriptions before if the panelists wanted.)
[Edit 1:21 p.m. EST: I've sent the above proposed description, with "regarding race, religion, and other forms of human diversity" added in to make it comprehensible without the context of the prior description, to Boskone's programming at its request; however, it may not be logistically possible to change it at this point, which I completely understand and sympathize with. I'd still like to hear people's thoughts about this, though, no matter what happens with this particular panel—it's not like it's a topic that can only be addressed at this one con, after all.]
[Edit #2, 2/11: desdenova formulates a much better proposed description in comments, to wit:
Much SF produced in the U.S. displays a lack of cultural diversity at odds with the reality of American society. Frequently, this lack can be ascribed to unconscious default assumptions made by creators. What are some effective strategies for identifying hidden biases in SF? How can doing so benefit us as readers, writers, and fans?
Which has been duly forwarded in case it's not too late to let the panelists see it and consider it.]