For me personally, I would only buy setting lore. I despise with the fury of ten thousand natural 1s how "kitchen sink" settings file everything that is interesting off a setting race and then leave it as some bare mechanical effects.
In Eberron a Warforged was a sentient weapon created under a monopoly by House Cannith but sold to all of the nations involved in the Last War. But the Treaty of Thronehold that ended the war both declared them free people, and closed all of the Creation Forges. So you have warforged who may or may not have served, who may or may not be used to the idea that they were not even slaves but self-guided equipment. They may support the Treaty that freed them, hate it as a slow genocide - or both. People are used to seeing them as weapons, and now see them as reminders of a war most want to leave behind. Some will still treat them as slaves, others try to "save" them.
In FR, they are metal men with some mechanical influence.
Heck, look at how Eberron or Dark Sun has refreshed the stale lore of other races and classes, allowing stories much different than the default.
So I dont' want any "generic" lore - I don't want to play in a game that can use it. So if you want me to have a chance to purchase it, make it setting lore.
All of that said, I homebrew my settings, something I enjoy doing greatly. So it's lore books for games I play in.
Like I started with: "for me personally...".