“A remind me of this message”-feature would be great, as it is described here:
Same idea, but different way are “global favorites”. You can use “has:stars” in global search, but as long you don’t know this, the favorites features stays per channel. But if you don’t remember the channel, where you favorites some message, you are unable to find it via the UI.
Both features are really important for information retrieval.
My usage scenarios where like this: I am on the road just having a little time to check the messages. I see some important message and I can decide, to get this message back later on as a reminder (maybe next friday before team-meeting) or I can add a star // favorit, so I can later on check all my favorites, what has to be done.
I also think this should be a core features. But I would be even happy with some plugin or app.