Am I the only one who doesn't see any problem with this at all? I mean, it's not like attendees are talking into a phone, inconveniencing other people. Complaining that every attendee's attention is not permanently fixed upon you strikes me as particularly vain. What about taking notes on a laptop? What about scribbling into a notebook? You should be glad that someone's interested enough to repeat the things you're s…
I read this differently: an audience can get the most out of a presentation by paying attention.
If you're consciously communicating while attending a presentation, you're probably not getting anything out of what's being immediately said. In an information-dense presentation, that means you're not getting the most out of the presentation: unfortunate at best, and making the rest of the presentation hard to understand at worst.
Perhaps it's more useful read as an "attendee tip" than a "presenter request?"