Ryan Stoughton said:
Bad 1 (GM is making a world without considering play):
"Well, a society at this technological level would have gaslight. Oh, and that means some piping underground. Well, just in case it ever comes up, I'd better map out the piping system, and figure out how each side of the river's gas lines work."
::snips example 2 because it is a bad example::
Good (GM is thinking about Threat/Reward/Asset/Problem as he does everything else, and uses that to manage his time):
"Well, a society at this technological level would have gaslight. How can I make that something more than window dressing? Oh, what if there's danger of a gas explosion? Maybe the players can take advantage of that by tearing up the cobblestones on purpose.
I don't really see these two things are at odds, without going to unrealistic extremes. The act of detailing a complex system like the underground gas pipelines doesn't preclude their use in play. Quite the opposite. Should the players decide, "Hey, gaslight! Let's use it to blow up the BBEG's house!" having those plans -- or more realistically, a set of notes about how the system is laid out -- will enable that play.
While I agree that filling in "details" at the expense of working on the "adventure" can do harm to the DM's campaign, I think you are presuming that every DM has the same limited preparation time as you do. Some people have lots of time, relatively speaking, and can afford to write out the history of some far off nation and still be prepared for next weeks adventure. And as an added bonus, when a player character bites it and a new one is rolled up, the player can say, "I want something more exotic" and the DM can respond with, "There's this place over here."
I also agree that player input is important and beneficial to a setting, particularly a long lived one wherein multiple campaigns will be played. But the opportunity for player input doesn't preclude DM worldbuilding, and nor is the opposite true. If the intent is to be truly collaborative, then that means the DM gets equal say. And it isn't like things can't be changed if they haven't actually seen time at the table yet, or retconned even if they have.
One of the reasons that D&D campaigns can be so rote and bland is that there's just enough implied setting to make everyone feel that worldbuilding, aside from a few funny named locations, is done. it isn't, not by a far shot. For a real glimpse into how inspiring worldbuilding can be, read the appendices to the Lord of the Rings, particularly the one on dwarves. It is full of epic history, and yet hardly restrictive if one were to use it as the background of dwarves, or something like it, in one's campaign.
In the end, I think it is better, particularly for a DM that tends to run off the rails and improvise, to have a well crafted world painted in large brushstrokes. It leaves enough room for everyone's creativity, but it also keeps thing consistent and maintains a level of versimilitude that makes games better.