The real take-away from this is what Fair Strides said. Multiple custom modules. A reskinned area can have dozens, if not hundreds, of files that normally go in the override folder. Any .vis, .lyt, .tga, .mdl, .mdx, .wok or .txi files used for the area model can be included. If you've got a mod like Brotherhood of Shadow installed with numerous custom modules, there are potentially thousands of files in the override folder that could be simplified by including them in the .mod file. Trying to dig through that override is a nightmare.
This is really just me trying to encourage people to start putting their module assets in the individual .mod files as opposed to duming the whole lot in the override folder, where it creates clutter.