There are two kinds of people that smoke - people that casually smoke weed but don't really go into it more than that, and people who treat weed almost like a wine connosseur treats thier wine. They notice and appreciate the nuances between different kinds, and include its visual appeal as part of the criteria that describe its quality. Amongst these people, there is appreciation for these things, and they like to share them amongst eachother.
Perhaps a question and an analogy to help you relate: Why do skiers post pictures of themselves riding? Surely your average schmoe who rides rentals twice a year doesn't really understand the facination, but amongst a group of people who appreciate it more than that, there is a desire to share amongst thier peers.
And yes, Newschoolers is a skiing website, but the galleries include sections for members other interests.
Straight from the thread, i believe this was said by Mauii. and i agree with him.