Why? Because I have lots and lots of file types... and many vendors don't care what their icons look like! If we standardized at least the shape and texture of a plain file, then there would still be room for original ideas AND we'd have programs that came with their own, appropriately-rendered file types. At least if ONE type of file is not possible... have a glossy set and a plain matte set. Keep the shape, and put the file extension in roughly the same place.
The only problem I have AT ALL in customizing my machine is the time I waste in worrying about some ugly file bearing its teeth and ruining the look of my machine lol
STANDARDIZE!