I like that idea. Although I don't think you'd see say, class builds proposed there (since a class is provided 1-30).I'd quite like to see tier-specific books, not tied down to any realm.
A book focused on the heroic tier, full of setting-neutral themes like Dungeoneer and Bounty Hunter, more heroic tier equipment, and origin stories (as per the Feywild book).
But since we didn't even see a DMG focusing on Epic tier play, I doubt we'd ever see a player book doing it.