One benefit is that you can remove yourself from a group conversation if everyone is on iMessage. If there is one person on SMS, there’s no way out (you can mut

One benefit is that you can remove yourself from a group conversation if everyone is on iMessage. If there is one person on SMS, there’s no way out (you can mute notifications, but if there are unread messages it will show up in the red number for the iMessage app. I don’t know if this is a result of Apple purposely making it impossible to excuse yourself from a mixed conversation. It would certainly be possible for them to make the unread count ignore muted conversations.