How about a Guild Hall!

[Wicka]

I really like the idea of a Shell hall, and I really like most of the ideas OP presented. The fact that the idea was so fleshed out is a testament to the thought that went into it.

There are a few things that I think may hurt the game a little though. While I do like the idea of have a workshop area that allows members to craft using facilities, I dont think that getting access to the master or intermediate facilities is such a good idea. That will make the crafting guilds obsolete aside from the quests you can do for them. I think that access to the basic facilities is a good idea though as you can get those just very easily anyway.

As far as making the world barren, I agree that people sitting around arent doing anything anyway, so no big deal there. And since the inns will be implemented soon, nobody is going to just sit idle in town anymore when they can simply rent a room and log out to accumulate that rested bonus. Having rooms in the Shell hall makes sense as well.

A final thought to maybe make the Hall a little more viable:

Instead of making most of those benefits free, make them simply discounted.
-500 gil instead of 800 for basic crafting facilities
-1 instead of 3 for a room (i dont know what the actual cost of inn rooms will be...)
-etc
As much as I would like that kind of thing to be free, I think it would be more efficient if it was discounted. More gil for the shell coffers and all. It also makes it less necessary to join a LinkShell. Some people, as odd as it sounds, dont want to join a group or are simply uncomfortable with that sort of thing. If you still have to pay for those things as a member, even at a small discount, then it doesnt seem like you MUST join a LinkShell to be able to do anything.

An instanced gathering place for a LinkShell would be awesome. I would love to see most of the ideas from OP implimented.