The problem is the big gray zone between spam and letters from Mom. All those mailing lists you get on because you signed into their website or thought something looked interesting once, and they're more or less behaving themselves but still more noise than you're willing to deal with most days.

Inbox dealt with that category of mail, which is at least 90% of what I get, in a simply beautiful way that I can't replace. Gmail has clunky tabs with 90s style pagination and ads at the top.