I enjoy your blog. i also respectfully think you may be in an echo chamber on this one.

Look at why people don't attend these:

1) they don't provide new info. if there is a nugget of something, it could have been in an email.
2) its a one way broadcast disguised as a conversation
3) all hands topics tend to be disconnected from the daily reality that ICs care about.
4) forced enthusiasm and curiosity feels inauthentic, and in fact is insulting at times. huge trust loss for that leader.
5) as you said, attention is limited to 30 mins. 'mixing it up' feels like a dungeon master trying to come up with novel ways to torture you.

What I know most ICs want:
1) keep them short.
2) share info we cannot get elsewhere. kinda impossible, as you need to send out summary or notes.
3) explain reasoning behind big decisions
4) q&a. haha
5) end early

Socially motived and extraverted folks love these. They seem to find them energizing. Also managers seem to love these too. In last 3 jobs, I have observed that managers and leaders contribute the most to meeting overload. They are getting paid to solve problems, but haven't figured out how to solve communication and dissemination in a way that doesn't kill the soul of the ones that love the craft.