A few solutions I can think of that would cut down on messages and increase the messaging systems cleanliness and purpose would be adding message support for priority, deleting, and threading.
Message priority:
When going through messages, it’s impossible to know which ones are higher priority than others.
This is a huge problem that makes the messaging system obsolete when you’re a creator that gets flooded with every type of message you can think of.
Instead of having all incoming messages being treated as the same, there should be some system of priority for what is checked first. Things that are of higher priority could be messages from verified users, replies to messages you’ve sent out, messages from friends, and then messages from followers. This idea should come with settings for users to choose what’s most important.
Deleting messages:
The archive system works well until you’re spammed and have hundreds of archived messages and the important ones that are archived are hidden behind and inside that mess.
The purpose of the archive should be to keep important messages. The idea of deleting messages would give the messaging system the organization that it needs while also presumably cutting down on data costs.
When a creator wants to keep relevant feedback on their creations in a contained space, they have no option other than the inbox. Spam and scam messages are usually always archived as a means to get rid of them which makes storing important things in the archive, which is its main purpose, is utterly useless because of how many unwanted messages I’d have to filter through to get to what I want.
Message threading:
Every time you reply to a message, it gets sent as a new message with the previous messages copied below.
This plays a role in flooded inboxes and presumably higher data costs.
Instead of sending a new copy of the message when you reply, it could instead shoot the message back to the top of the inbox with the reply inserted at the top. This way when two people send five messages back and forth, they don’t have to archive all ten that are now in their inbox.