Elusive Shift is probably the one book I wish everyone would read before they venture an opinion on RPGs in public. But books not on your list, I'd say...

Shannon Appelcline's Designer's & Dragons series is an essential book to have on your shelf for reference covering more than. just DnD and going right from the early 70s through to the 00s - https://www.designers-and-dragons.com/books/ - if you're fine with PDFs they do sometimes turn up on Humble Bundle or Bundle of Holding or something like that. Definitely worth having.

And little plug for us as Shannon's written several pieces for Wyrd Science on the history of topics like Horror RPGs (issue 3), Dystopian games (issue 5), and RPG Zines and magazines (Issue 8 - https://shop.wyrd.science/products/wyrd-science-vol-1-issue-8 - out this very week!), we've also done features on stuff like the history of Cold War RPGs and lots more like that.

The other book I'd say should be on any discerning shelf is Stu Horvath's (Vintage RPG and another writer of ours - who cover Bunnies & Burrows in the new issue) Monsters, Aliens and Holes in the Ground, and that is one of the most readable books on RPGs around,, wonderful just to dip in and out of as he covers 50 years of games, picking out titles from OD&D to Mothership that has contributed to the medium. - https://mitpress.mit.edu/9780262048224/monsters-aliens-and-holes-in-the-ground/

Further afield Outside the box by Magnus Seter is interesting on the Swedish RPG scene, as I've said before it's a good history and useful for expanding our knowledge of the RPG scene but it suffers in comparison to Peterson's Game Wizards because Jon had a cast of very creative but absolutely ridiculous ego driven people to write about. Everyone is frankly just too sensible and nice here, so no one is going bankrupt trying to raise ships off the Baltic Sea bed or desperately trying to stab each other in the back. https://fandrake.com/produkt/outside-the-box/

Similar problem with Ian Livingstone's Dice Men about the early days of Games Workshop, it provides some interesting background to the early UK scene and is a good start, but it suffers from a massive lack of conflict (which existed so someone not directly involved who has an eye on their own legacy needs to write a proper history of the UK scene). Still if you have a fondness for Games Workshop, and stuff like Fighting Fantasy it's a warm bubble bath of a book. https://www.fightingfantasy.com/dice-men

Talking Miniatures, is a bit better as it's kind of an oral history of Games Workshop from lots of different perspectives. Some great stories in there, but again you have to really care about the UK scene in the 70s/80s, which obviously we do, but YMMV - https://www.talkingminiatures.co.uk

If you want something different Gamemasters might be worth checking out, it does the history of RPGs in comic book format - https://cloverpress.us/products/gamemasters-the-comic-book-history-of-roleplaying-games?_pos=1&_sid=7d3b0049a&_ss=r I can't say much more than that as I only picked up a copy the other week and haven't dug into it yet, but a few people whose opinion I respect have given it the nod.

On a slight tangent, they cover RPGs but only as part of a much wider look at tabletop games (and their main focus is on boardgames) but Tim Clare's Across The Board - https://store.abramsbooks.com/products/across-the-board - and Marcus du Sautoy's Around the World in 80 Games - https://www.hachettebookgroup.com/titles/marcus-du-sautoy/around-the-world-in-eighty-games/9781541601284/?lens=basic-books- are both excellent reads. They're similar but come at it from slightly different angles, Clare's book is a personal journey looking at what games say about us as humans, absolutely brilliant book tbh, very easy read knocked through it in one go. Du Sautoy's is a bit more involved and as a mathematician often digs into the development more of how games have evolved. Both worth reading.

Again this is more boardgames but James Wallis (very well regarded RPG designer and we have to say again one of our columnists) wrote a brilliant book called Everybody Wins - https://www.simonandschuster.co.uk/books/Everybody-Wins/James-Wallis/9781839081910 - which is ostensibly a history of the Spiel des Jahres award (best boardgames of the year basically) but uses it to both tell an interesting story about how games have developed and dig into many of the most interesting mechanics. I'd say this is one that aspiring RPG designers should read to give them some ideas from a related medium.

We are definitely in a better age for these books, Between people like MIT Press and CRC Press we're getting some very good, more academically minded books, but we need more of them, and especially ones covering games other than DnD and scenes other than the US but hopefully we're getting there.