Science vs applications would be actually a good way to divide NeurIPS into two conferences to get focus back: NeurIPS and Applied NeurIPS. One wold present science, the other tweaks, tricks and methods to solve everyday problems.
Papers like "Partially Encrypted Deep Learning using Functional Encryption", "Dancing to Music", "Differentiable Cloth Simulation for Inverse Problems" would go go the engineering conference for the "most people".
I don't agree about this one. It does seem fundamental science to me.
A big problem was cramming hundreds of posters in one large space, with a relatively poor search experience (posters were kind of arbitrarily organised with some categories only having three or four entries). If they'd split them over both exhibition centres (or multiple rooms/floors), it might have calmed the crowds. Also since it was hard to know exactly where to look, there was a lot of wandering around.
There's also the heavy corporate side where people spent the evenings going to not-so-secret invite-only parties (lots of FOMO going on). Lots of jobs going, but ridiculous amount of competition now.
Despite that it was pretty friendly, and I had good results emailing people I wanted to chat to, and going to the socials.
Really the field needs to start publishing in journals again, and not obsessing over one or two mega-conferences each year. In other domains, there are huge congress events, but they're much more informal (eg EGU, 17k people).
However, I was still able to talk to everybody I wanted to talk to - often for long periods of time. Many of them I sent emails to, and I was able to talk with everybody I wanted to (except 1), many who would be considered senior researchers.
Disseminating scientific ideas is really only one part of what a conference is meant to do. The other part is networking, and that was extremely valuable for me.