I think we can succeed in using mail for clarification (like we're
doing now). We all just have to be willing to look stupid now and
then.
One picture often says more than a 1000 words.
Pictures can be sent (by reference, one hopes) over mailing lists as
well. But it's more than that; it can be a lot more efficient to
learn by watching someone talk about a topic than by reading about it.
Otherwise college lectures would have died soon after the printing
press came into vogue.
Still, I think the tradeoff is in favor of not having presentations
during meeting time, with the occasional exception. There is a whole
lot more non-meeting-time out there than meeting time; therefore,
making people do an hour's worth of reading to save twenty minutes'
worth of in-meeting presentation is probably a good thing.