So, as PLAYERS (as DMs, sure, as that's where a lot of our fun comes from), do you really care that much about the game world?
I am interested in many things
in the game world. I am interested in my PC, the other PCs, the challenges of our adventure, cool NPCs, and the elements of my PC's connection to the game world (enemies, loyalties, factions, etc.).
But the world itself, independent of my PC's interaction with it? Generally, no. It isn't that I can't get excited about the details of a setting--I have delved deeply into the lore of many fictional settings. But:
a) Before I care about a setting for its own sake, I have to engage with characters/story in that setting.
b) The setting has to be fleshed out and internally consistent. Many DMs are not good at this.
c) The setting has to have a "bible" that I can peruse at my leisure. When I'm at the game table, I am focused on the adventure at hand, not random backstory.
d) The setting bible has to be coherent, understandable, and
concise. Most DMs really, deeply, terribly suck at this. Especially the last bit. And the more enthusiastic they are about the setting, the worse it gets.
And that's coming from a guy who loves world-building for its own sake. In my experience, most players don't. They simply do not care about anything beyond the adventure at hand. Any world-building that I do as DM is done for me, not for my players.