Anecdotally, my own current UI gripe in iOS messages is identifying different variations of groups containing mostly the same people.

- My family - My wife's family - Both of our families - My family but only those nearby - My family but only those attending a specific event - My family but minus one person

The current "facepile" approach really fails in distinguishing them... we've all been making mistakes sending messages to the wrong subsets.

I know that it's possible to name groups, but it's not something that I always remember to do (or care to do, for a transient conversation)