Pretty simple one here which I am sure will make sense to most of us.
Firstly - why am I seeing messages from 1 year ago atop my inbox on messaging? It's a mess, also - moving messages I have responded to to the top of the inbox is a big flaw, please can we just have threads with newest replies from the sender restored to the top, just like a normal email account - makes it so much easier to see what I've missed. Actual dates as opposed to "3 days ago / 3 months ago" would be helpful.
Secondly - I love receiving demos from other artists in my inbox. I think a "send demo" button could be a great addition to our profiles. Allowing artists to upload a private file only sent and stored in the inbox of the recipient - I know this is possible in messaging non exclusively but a seperate tab for demos in the inbox would segment the items sent specially to you, highlighting their importance as opposed to any copy & paste jobs in the regular inbox.