I'm not talking about manually tagging, setting up, and filtering all incoming email before my inbox can self-organize. I mean automatically. Only show me the true primary items in my inbox from the jump. Everything else can wait.
In the absence of this feature my inbox becomes a torrent of incoming mail that is far harder to manage and prioritize. I keep my inbox at "zero" and I can completely understand why other people give up and let their inbox be overrun. This feature is essential for me.