Photography is unique in that it attracts a lot of left brain people. You don't see this in painting or sculpture to the degree that you have in photography. I think it's a win win situation. Right brained people are flexing thier left sides and vice versa. It brings together a group of people that wouldn't normally hang out and ends up helping each other learn in areas the other needs.
The left brain side of photography warrants a lot of testing and discussion of what is being tested and the results. Photography can be very technical and I find that I'm engaging that side of me more and more. All that chemistry is cool-especially when it works! You wouldn't have been able to bribe me into a chemistry class in school but now I seek it out.
I also think photography is very approchable. You can get results fairly quickly and can be engaged on any number of levels or interests without really having to live up to an "establishment". Some are primarily interested in "documenting" while others are "fine art" minded and everything in between or otherwise.
I've noticed a lack of esthetic discussion as well. For some reason it's a little tricky to get this going here. Maybe it's the format. So much of the emotion needed to convey these kinds of ideas are hard to get across while typing. I loved the critiquing sessions in college but wonder how that would really translate to an internet forum.
Bottom line for me is there is a real need for right brained discussion on APUG but I'm not sure it's possible. I'm glad for what I can get (which is a lot) and I'll let the rest work itself out.