I know SMS is low priority, because it is inherently insecure and open ..
But a BIG feature would be if the bubble icon color matched the contacts color.
Even on an insecure communication channel, sending a message to the wrong individual could result in issues. (Unrelated to the security of the message)
Ie: Bob knows 4x Alice's ... Color coding those contact icons allows Bob to know he's not texting ex-girlfriend Alice, or boss supervisor Alice, but rather sweet cousin Alice, etc ...
This is important for groups, or individuals with long names. Since it's already built into the Contacts, and used by the Dialer, hopefully it is easy to add to Messages with minimum impact on codebase or attack surface