Looking at my girlfriend's gmail Inbox makes my eyes bleed, it's a mishmash of seemingly irrelevant email, lots of promos or facebook notifications more than half of which is unread. I sometimes find it hard to control myself not to "clean it up". This seems like a perfect addition for her... as for me, I've already setup my filters and am already happy with gmail as is; I don't think this will interfere with that. Seems like a feature designed for the 99% of people who don't frequent HN.