Are there docs or maybe a blog post that identifies the value-add on top of Express? While I see the API design example (which applies to me), we already do tha

Are there docs or maybe a blog post that identifies the value-add on top of Express? While I see the API design example (which applies to me), we already do that with Express v4 (it's more code organization than anything else.) I'm super-interested, but I'd like to know at a deeper level what this gets us over plain Express.