Sure, could be neat.
Though I will say, just as a personal preference, that I like having world specific lore, especially if there's multiple variables, over world neutral lore. I get that the latter is more intended for world-building, but I find the former to be more valuable for that purpose.
Where world lore goes will always be a big question for me. I so my own world building but I've also grabbed bits and pieces from various sources. So for non human races I use Greyhawk (with a few tweaks). For humans I make my own and it varies by region - although most of my campaigns are set in an area that follows the same pantheon.
So I'd like a book dedicated to different religions, including some that aren't polytheistic. Something like the old Deities and Demigods. But I see that as a supplement, not a core book.







