I think you bring up a very interesting subject! Over the past decade, Kishimoto has built an impressively large, dynamic and fascinating world in NARUTO, but he often does not spend time exploring minor lands, clans and characters, which is really a shame because there is so much potential for storytelling in his world. However, we must realize that Kishi is under the gun when it comes to his writing and drawing. He is creating for his audience, sure, but most immediately he must please his editor, publisher, and the list goes on because he is atop a huge international franchise. For this reason, Kishi simply does not have the flexibility a traditional fantasy writer enjoys to deviant from his or her main characters and/or plot lines. Naruto and friends are who have sold manga volumes, DVD’s and figures up to this point. So Kishi is expected to stick with the program and keep his story focused, especially since he publishes a weekly comic where the typical Japanese fan demographic averages to be 13 years old.
If Kishi had his way, I would like to think we would learn more about the fascinating “minor” settings and characters in his story because these often serve to breath even more life into a fantasy world. Perhaps when Shippuden finally concludes we can wish for a published volume of assorted tales.
Thanks for your question!!