I think Rust next should at a minimum try to include 2-3 new nifty features because users love new features. On top of the improved infrastructure (improved build times or whatever), this should by default meet the suck less criteria.
I mean speed and such is always nice but when looking at release notes to decide if you should upgrade (especially if it’s already satisfactory), new features always tend to look cool and sparkly .
[EDIT] I’m not picky currently about which features get included though. A lot of things would be nice I’m sure.