There is a direct correlation between what Xur brings and the community.
The quality of items Xur brings each weekend is directly related to the power of the Destiny community's dance. The more people dance and the longer they dance the more it appeases Xur. Dancing increasing Xur's spirit to bring us better better items.
Think about what Xur brought early on in the game and what the community was doing! That is right... We were dancin' and Xur brough Gjallahorn and Ice Breaker.
Come on community. Keep the dance going! Stopping by the tower.... Dance! Patrolling... Dance! Crucible and owning... Dance! Fighting Crota or Atheon... Dance like you mean it!
Upload screen shots of dancing with something awesome going on in the background. It will encourage Xur to bring Gjallarhorn and Ice Breaker!
Dance Gaurdians, dance!!!
-
I do believe a limited number of exotics is given out per day per geographical land mass but I don't think 1 aspect of the game affects another.