So why is it that every time I see an adventure rider on a dirt road they are standing up?

Is it just for a better picture lol, or is control improved that much by standing is it always needed?

When I rode my dirt bike as a kid, I only stood up like that on real bad trails... but not the smooth dirt roads that I see these pictures of..
For example this picture taken from One Wheel Drive. Net:
http://www.onewheeldrive.net/wp-content/uploads/2011/04....

I gotta fix that link bug.  

Yea, I suspect it's mostly for the photo. I typically only stand if the terrain is rough. Most dirt roads I've ridden don't merit standing.

Yeah, I'd have to agree--standing is dependent on what kind of terrain you're riding over at that moment, or perhaps needing to see a bit further down the track if you're unsure about what's ahead.  I suspect standing shows up in a lot of pics because the editor or writer feels that it makes for "more interesting" pictures.