Is there an official Workshop user page for Valve, kind of like how you and I have one? How about official ones for any staff member of Valve? If not, why not? I ask because remember the teasers for each new element back in 2010? Like these:

Videos
http://www.youtube.com/watch?v=1oVpE40V9rE
http://www.youtube.com/watch?v=fE3B9uGnVlA
http://www.youtube.com/watch?v=yFRbGppLaUI
http://www.youtube.com/watch?v=DOH6BprN9FI
http://www.youtube.com/watch?v=a7V0HBwHfEw
http://www.youtube.com/watch?v=Pcf99_DZZew
http://www.youtube.com/watch?v=laxPhiDqTJA
http://www.youtube.com/watch?v=IaZ75vU112Q

Some of these chambers made it into the single player story mode and others did not. Wouldn't it be nice to play those missing chambers instead of looking at the YouTube video or relying on fan recreations? Sure, the Workshop may have been designed for the players who wanted to contribute something to the games they love rather than the developers, but that didn't stop YouTube from creating their own channel for example! Also we watched the solving of those chambers so why play them? Why not explore the chambers further than the videos demonstrate? This could possibly get Valve to pay more attention to Portal 2 by releasing more content or fixing bugs with the current build of the game.

Am I making any sense here?

I don't think there is an official one,different valve employees have their own workshop pages though
they might even have stuff on it.

But I don't think they have all the trailer maps out there. Keep in mind that the video's were from a product that was fully in development, it's very likely the maps they were in actually weren't playable other than the part that has been made.

The only things that really didn't make it in was the pneumatic level (cause element scrapped)
The propulsion level: not really an interesting puzzle, but a good demonstration of the concept.
The repulsion level 2: once again a good demonstration but not really interesting to play.
The other maps all made it in to the final product in a slightly adjusted form.

Links, if possible?