All of the features that your requesting have a use but only in channels with less that 10 active chatters at one time. Editing messages of users would (beyond a lot of other problems) take so much time for so little achievement. The message would be off the screen in 30 seconds tops for an “active chat” and you run into edit messages under others names. Freedom of speech is what makes Twitch, Twitch and editing others messages ruins that.
"ability to create more interactive bots"
People are creating more and more interactive bots every single week. I’ve seen bots with rock, paper scissors that are optimized to work well in chat. There is always some sort of solution in a problem.
"filter out unwanted spam"
There are sooo many ways to handle spam. bots, Twitch’s Banned word filter with both links and spam. Surely there is something that can meet your needs out there. Also links and long paragraphs are there to prevent spam so it’s always up to the streamers discretion.
And I’m really sorry but I do not see any point at all for the ability for pre-screening messages, Twitch isn’t the TSA at airports. And for streams with >10 chatters that pre-screen will instantly be backed up too the moon and there is just no good way to handle that situation at all. Stream chat is used to add “liveness” to interact with viewers. And pre-screening would turn it into a Youtube video with a forum type chat. <- Bad
Hope this “opens your mind” to why these features should not be added.