MMOs and story (opposite approach)

#1 Very different?
I love to ramble... so read on at your own peril...
Rewarding social interactions with in game currency and increasing trade relations would probably create a growth cycle. The more you interact, the more valuable you and your work should/can become.
Much like becoming a master artisan, the longer you do this, the better you get at doing it.
However, unless you have a lovely little "bauble" item that was "created by PlayerX" this sort of social creation would either spiral out of control, or become pointless as only true artists who created real content would create anything of true value.
There could possibly be an ingame creator that allows a player to interact with an object, the previously mentioned Bauble and change properties to increase its value. And as the player furthers their own story, more modes and changes become available to that specific player. So not all players would have or be able to open up all the different Bauble modifiers. You could then truly own PlayerPicasso's masterpiece. It would need to receive its own unique stamp or some suitable marker to uniquely identify it should the player decide to create another duplicate. Imagine if Davinci had been coerced into making more than one copy of his mona lisa, or say someone actually stole the mona lisa, and used some Uber-Mad-Skillz and created many copies which said thief could then sell to many buyers.
This way, even houses could become works of art that get traded around...
"Wow awesome cottage..."
"Yeah, its a PlayerPicasso number 1 limited."
"Can I buy it?"
"Hmmm, I don't know it's a limited..."
"I'll give you a million..."
"Well, alright."
Obviously I'm inflating here, but the point is similar to true art, value is in the eye of the beholder. I wouldn't buy a Picasso, but I might buy a VanGogh.
And as a player advanced, and created more works some of the older would gain some in game value since the player is doing something different.
There could always be multirun items like lithos are now-a-days.
Anyway... ramble ends...for now...

#2 Oh, I was assuming that "only true artists who created real content would create anything of true value" - why would that be pointless? But your idea is very interesting.

Personally I think, rather than buying a whole house it would be more fun to buy the plan for that house and/or any of the special materials for that house, then build your own version.

#3 I think that when creating story for a deathless static world, _modularity_ is a very important concept. The model to look at is sitcoms - they manage to have something different happen every week, which feels meaningful to the audience without actually changing much in the story world.