For one, content creators need to be able to set up channels for different types of content, so that their content can be better organized. Two, there needs to be a notification and subscription system so I can know when a person I follow posts something new. Three, content creators ought to be able to edit posts after the payout. Edits would not garner any new rewards, and previous versions could still be visible, but sometimes things change and it is better to edit an old post than make an entirely new one.
Those are just the few off the top of my head.
RE: Why Steemit will fail, I am back from the future with some advice.