The Shadow
Hero
In reading the last few pages of this thread as it has evolved, it strikes me that the 'problem' is that everyone is (partly) right. 
Default lore can be a big help to new GM's. To a newbie, the prospect of creating a whole world from scratch can be very daunting and a barrier to entry. The 'official' lore gives them a base to start from, and sparks ideas toward fitting it all together in their own way. (Also, the newbie likely won't have all these old campaign settings from the past to draw from, either.)
The problem arises when players absorb the default as being 'The Way Things Are'. Experienced GM's don't need the defaults, and at most mine it for a few ideas, so can find it a hindrance when their players have mismatched expectations.
And while experienced players can generally roll with the punches if the GM tells them things are different, there's people who don't do it as well. The highly amusing post above that described halfling worship of Yondalla as 'generic' is the poster-child for this.

Default lore can be a big help to new GM's. To a newbie, the prospect of creating a whole world from scratch can be very daunting and a barrier to entry. The 'official' lore gives them a base to start from, and sparks ideas toward fitting it all together in their own way. (Also, the newbie likely won't have all these old campaign settings from the past to draw from, either.)
The problem arises when players absorb the default as being 'The Way Things Are'. Experienced GM's don't need the defaults, and at most mine it for a few ideas, so can find it a hindrance when their players have mismatched expectations.
And while experienced players can generally roll with the punches if the GM tells them things are different, there's people who don't do it as well. The highly amusing post above that described halfling worship of Yondalla as 'generic' is the poster-child for this.