I think it’s always a bit of a compromise. I run 780s, there’s one place on my local trails I’ll usually scrape one or both ends of the bar*, so I reckon I woulnd’t want to go wider.
If I could be bothered, I might cut them down to 760 or so, I know that 720 feels a bit narrow (although I’d run something like that that if I had more tight gaps on my usual rides), but it’s splitting hairs really. It’s not surprising that people aren’t just going bigger and bigger, we’ve been obviously approaching a limit for a while, and some people are bound to want different widths than others.
*I’m actually surprised my riding mates with narrower bars haven’t gone searching for something with more width restrictions.