I'm A Banana
Potassium-Rich
Well, of course. The question is, when the players point at the map and say, "What's here? Let's go there" and you haven't planned it out yet, your choices are (a) draw from your boundless, unending creativityblush
and just make it up on the fly, (b) open up a published module, or (c) roll on some tables and never stop the game.
One thing some more modern games have tried is (d), have the players tell you what's there.
So the answer to "What's here?" is the question, "What should be there?"
Or the less empowering, but still player-driven, "Well, since you've got a Blacksmith background that hasn't been used in play yet, lets say that there's a famous blacksmith living int he town there."
It leads to a very collaborative game, and takes the pressure off of (a), (b), and (c) to be perfect. It does blur the lines between the DM's responsibility and the players' responsibility, but not all groups think that division is all that important anyway.