The Phandelver Starter Set is still selling briskly at my local Target, after 5 years of release: that's pretty astounding, and doing a setting box as a "next step" alongside the revised Essential Set seems like good business.I think you’re right, and also I really think that Eberron has the broadest potential appeal to people just diving in to dnd.
It it doesn’t matter to such a person who hat the history of dnd is, so “most generic form of dnd” is irrelevant. It hits fantasy notes in a way that is very popular today, especially in cartoons and video games, mixing genres, not running on medieval sensibilities, etc, it’s a fun setting that can also be played as dark or gritty as you want, and it facilitates the sort of weird, flashy, adventures we see in stuff like She-Ra, Adventure Time, Guardians of The Galaxy, etc.
And a lot of people come to fantasy gaming via more general gaming and nerd culture, and so are more/just as familiar with steampunk, noir fantasy, sci-fantasy, and other fantastical genres of speculative fiction that Eberron takes inspiration from.
Basically, I think that an Eberron box set with the classic image of the warforged hanging off the side of an airship, or the aerial battle in Sharn, on the cover, in big box stores like Target, would sell like hot cakes after a hunger strike.