This is really just wasting 20 minutes, it's much better to have a clear agenda which is basically in the form of bullet point notes that most people would make outlining the important topics and questions. Then just go through the agenda providing a brief elaboration on each topic and take questions, get agreement, write down the conclusion and move on. If the meeting is purely informational then in most cases you shouldn't even have a meeting.
Tufte makes a decent case for why it should be prose. But then, as an academic, it comes easy to him.
As you say, sufficiently self-descriptive bullet points should communicate equally well.
I find that whenever I go to that level of detail, I end up mentally with a prose narration at the leaf level, so I transfer that to the doc. This fills in some important connectives, such as "finally", "on the other hand" and asides such as "this is a minor point that should not affect the final outcome". This is helpful for people who may not have you around to explain. I also tweak that document after the meeting to fill in answers to questions that were asked.
Equally, for an important meeting, it is not enough to be an agenda. The content is important. The audience for the presentation should be people who are not in the meeting, but could have been (people on vacation, people promoted to the appropriate level, future hires).
