Just some people are picky when it comes to their mods being "clean"
It is not just about being "picky". This has actual ramifications when you have your city/lanscape mods in your load order. A record/reference in an esp will ie. determine a position of a certain object in a town or a dungeon cell. Even if the record is identical to the record in the Skyrim.esm (and especially then) all changes for that record made in another esp will be disabled depending on the load order. Since these dirty records are unintentional, they are usually unknown even to the mod creator himself. This will thus much unwanted and unnecessary headache when you have several dirty mods in your load order. So it is
not just nitpicking, dirty mods are a pain in the ass and are serious first world problem.