Yes, thisI enjoy the lore, but I'm not married to it, and it's all just a tool to build something of my own anyways.
Depends.I mean that latter stuff can be great for our own sense of the setting, but is it really for a better game for our own amusement?
Depends.
If a player says they want to research famous magical swords to go quest after it is nice to have some existing stuff like Black Razor for the sage/bard/oracle to reference.
If your players only react to what you put out and do not come up with their own topics to explore then Black Razor is useful to the extent you tie it into your existing or planned adventures.
That said, every edition of D&D brings new rules and new assumptions, and settings should adapt to those edition's assumptions if they are going to support the game. I would be very cross if (for example) a 5e Mystara setting didn't allow dwarves to be wizards because "they weren't wizards in Basic". That is lore that needs to adapt to the 5e paradigm of any class, any race. Similarly, I'm fine with any WotC setting introducing tieflings and dragonborn in them even if they didn't have them prior to 4e because that's what's in the PHB. Settings serve the game, not vice-versa.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.