Should an ecosystem that touts transparency as one of the key factors of blockchain be transparent about the speaking fees/expenses paid to keynotes as well as panelists? (At least averages that could be broken down by age, race, and gender would provide insights that could help the community make more informed decisions about where they put their advertising and engagement dollars.)

Not a bad idea.  But speaking fees are driven largely by celebrity/publications status more than anything else.  If they don't fall into one of those two categories then compensation may need to be reconsidered.  I recently chaired a conference for IEEE and we had some high profile speakers, but paid no speaking fees at all and only compensated travel for a couple of them due to distance.  It is the policy of IEEE and many other organizations to NEVER pay speakers!  Adopt the same policy and you'll level the playing field pretty quick!  There's always someone else just as good - unless a certain speaker is needed for a strategic/marketing reason.