You raise good points, but the points I mentioned are just as valid for a sandbox approach.
Fantasy settings are bit more of a gimme when it comes to the three questions, mostly because most people have the tropes of the fantasy genre ingrained into them.
For some examples from the text:
- It's not until page 31 that a list of the races available to PCs appears, and the descriptions are less than dozen words each. What races are significant and which are less prominent? What are the cultures of each of these races like? Why would you want to play a kuo-toa vs. playing a lizard man? Your example games (Tekumel, Atlantis, and Talislanta) are all rich with information about the different races, and most of them have around a dozen or so races to pick from, as opposed to 62.
- There are 546 professions listed, by name only. No real advice about how they fit into society, or which races favor which. With so many options, why list them at all? Again, the sandbox games you recommend usually have either freeform character creation or introduce thematic classes/professions/careers that make sense and work within the setting.
If I were an editor looking at this, my first piece of advice would be to look at the GM advice on pages 114-118 and say "Pick one of these themes and rewrite the manuscript to make the game about that", then leave the rest in the back as alternate modes of play.
The game I found this closest to in spirit was Shadowrun, and that game allows a vast amount of character variety but still gives some nice themes about what the players are supposed to be (fringe-dwelling mercenaries and for-hire entrepreneurs), what they're supposed to be doing (sticking it to The Man, if the pay is good), and what forces oppose them (corporate security). I'm generalizing, but not by much.