I think we could improve these events with some little tweaks that would make the experience of every attendee better.
- Manage the noise level. This is the most important thing. Noise must be low during the "networking phase", which means that the venue should not produce too much sound acoustically (and if it's not possible, simply reduce the number of people attending your event). People should be able to talk to each other at more than 20cm away after a talk. I can't count the number of times I approached a group, finding that I couldn't hear one single word because the room was too loud.
- Get 3 mics at least. One for the moderator, one for the speaker (or group of speakers), and one for the audience. The audience also wants to listen to the questions. The speaker or moderator should repeat the question after hearing it anyways, but this common practice is often forgotten, unfortunately.
- Fresh air access. This is more for conferences, since meetups are usually shorter. There's nothing worse than not being able to go outside for a few minutes every hour. Headaches and odors await otherwise.
- Find ways to nudge people to talk to each other. There will be groups of people that know each other, so the task is, by default, harder for strangers. Give them help, find ways to make interaction more natural. It's not that hard, I think (but it depends on the venue and what your event is about). For conferences, what I like is when other activities are offered (games for examples) — it's good to have breaks. And many times you can meet new people more easily in a different setup.
- Reduce. The. Number. Of. Attendees. I get it that organizers don't want a small number of people at their meetups or conferences. It's not as profitable and it's not as good for the press/reputation, but participants will thank you. 1) It helps people talking to each other after a talk. 2) It reduces noise. 3) It creates intimacy and makes people ask more questions to the speakers. 4) And, in fact, it reduces your cost and makes everything more manageable.
There're many other things to do, but these are my main frustrations. For the rest, the talk linked above is excellent! :)