I'm going to call "psychology" on this one.
A couple points...
- When I ran the band I learned something. I would switch the sim over during the winter to a snow covered, cold feeling sim to reflect the current weather. I would do this in about Nov. I would then flip it to spring in mid- end Jan. Obviously winter is far longer than 2 months, but I discovered that when the sim felt cold and uninviting people wouldn't play as much. I played with this idea a bit and figured out that people like the feeling of warmth and greenery. It's a subconscious thing, but people like having trees and flowers and green things around them when they play.
In my mind that is one of the reasons sims built off the structures of the Middle East always flounder. Because, like it or not, people start feeling dry and uncomfortable being there. (Yes, I am speaking in general here). There can be palm trees and full flower beds, but the general feeling of heat and dryness turns people off... it just does.
- In Gor, we have a hard time stepping outside of what we know. I think we forget this is supposed to be an alien planet. We tend to lean towards things we know. I think this is part of the reason you don't see alien plants on sims. Also, beyond a rare tarn or two, when was the last time you say tharlarians regularly roaming a city? When cities are built or lived in or run, we immediately hold them up to the nearest earth city we know and try to run them that way. Going to be a Torvie? Go learn about Vikings. Want to join Ar? How's your toga inventory? It's not a bad thing, it gives us a basis to begin play from, but I don't think we push hard enough to get out of the known.
All that said, Schendi is a rough one because we don't have an earth culture to immediately compare it to. Previous discussions suggested Ancient South American cultures, or African. The landscape of the Jungle would point towards, geographically, something like deep Africa, or the Amazon. I can understand, because of this, why someone would naturally assume Mayan or something akin when it comes to a city, because these are the only massive cities we can base things on in these areas.
(And before anyone freaks out, yes I know there were massive cities in Africa, but they are far less known and most of their structures are gone leaving us little knowledge about them.)
In short, because we don't have a well known, massive African city to base these book cities on, people twitch and don't go in that direction. So people might lean towards the unknown (South American) to get as close as they can, but really, it doesn't quite fit either.
I am sure we will continue to see middle eastern based sims, but I don't think people will ever get away from their natural inclination towards water and greenery so I don't see one of these sims ever taking off.
Someday, someone will build a Jungle based city. It will have the water and greenery I think people need. The trick will be if they can simply immerse themselves in what is there, and not try and compare it to something known to provide comfort in their own minds.