If you are fiddling with lots of tiny pieces (imagine Lego, or watch components), you necessarily need to find every piece you use. If they are organized beforehand then it is much more satisfying and efficient to assemble since all the searching is done beforehand. Think of how it is sometimes much easier to process a list after sorting it.
Organizing Lego as it comes out of the box moves all of the frustration in model building to the beginning of the experience, and removes it from all the rest.
